Implement internal mail skill MVP

2026-06-06 22:28:36 +08:00
commit 097df73495
22 changed files with 4059 additions and 0 deletions
--- a/.env.example
+++ b/.env.example
@@ -0,0 +1,28 @@
+MAIL_ACCOUNT_ID=default
+
+POP3_HOST=
+POP3_PORT=110
+POP3_USERNAME=
+POP3_PASSWORD=
+POP3_USE_TLS=false
+POP3_TIMEOUT_SECONDS=30
+
+SMTP_HOST=
+SMTP_PORT=25
+SMTP_USERNAME=
+SMTP_PASSWORD=
+SMTP_USE_TLS=false
+SMTP_USE_STARTTLS=false
+SMTP_AUTH_REQUIRED=false
+SMTP_ALLOW_INSECURE_AUTH=false
+SMTP_FROM_ADDRESS=
+SMTP_FROM_NAME=
+SMTP_TIMEOUT_SECONDS=30
+
+DATA_DIR=./data
+DATABASE_PATH=./data/internal_mail.db
+RAW_MAIL_DIR=./data/raw
+ATTACHMENT_DIR=./data/attachments
+
+HTTP_HOST=127.0.0.1
+HTTP_PORT=8765
--- a/.gitignore
+++ b/.gitignore
@@ -0,0 +1,5 @@
+.env
+.DS_Store
+dist/
+data/*
+!data/.gitkeep
--- a/18
+++ b/18
@@ -0,0 +1,18 @@
+.PHONY: test e2e build cross-build clean
+
+test:
+	go test ./...
+
+e2e:
+	go test ./internal/e2e -count=1 -v
+
+build:
+	go build ./cmd/server
+
+cross-build:
+	mkdir -p dist
+	CGO_ENABLED=0 GOOS=windows GOARCH=amd64 go build -o dist/internal-mail-skill.exe ./cmd/server
+	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o dist/internal-mail-skill-linux-amd64 ./cmd/server
+
+clean:
+	rm -rf dist server
--- a/README.md
+++ b/README.md
@@ -0,0 +1,317 @@
+# 内网邮箱 Agent Skill MVP
+
+这是一个本地运行的邮箱 Skill Adapter，面向 Agent 暴露结构化 HTTP 接口，底层使用 POP3 收信、SMTP 发信、SQLite 保存本地索引。
+
+## 重要边界
+
+- 本项目是 `POP3 + SMTP` 模式，不依赖 IMAP、网页自动化或邮箱数据库。
+- POP3 不能可靠同步服务器侧已读、未读、文件夹、标签、归档、草稿状态。
+- 已读、已处理、归档、删除、已回复、标签、草稿、已发送记录都是本地 SQLite 状态。
+- SMTP 发出的邮件不一定会出现在 Webmail 的“已发送”里。
+- 如果将来需要和 Webmail 已发送一致，可以改成调用 Webmail HTTP API，或者发送时 BCC 自己。
+- 默认绑定 `127.0.0.1`，不要把服务直接暴露到公网或共享网段。
+- 附件真实路径不会返回给 Agent，接口只返回 `attachment_id` 和附件元数据。
+
+## 配置
+
+复制示例配置：
+
+```bash
+cp .env.example .env
+```
+
+按内网邮箱配置 POP3 和 SMTP：
+
+```dotenv
+MAIL_ACCOUNT_ID=default
+
+POP3_HOST=mail.example.local
+POP3_PORT=110
+POP3_USERNAME=your-name
+POP3_PASSWORD=your-password
+POP3_USE_TLS=false
+POP3_TIMEOUT_SECONDS=30
+
+SMTP_HOST=mail.example.local
+SMTP_PORT=25
+SMTP_USERNAME=your-name
+SMTP_PASSWORD=your-password
+SMTP_USE_TLS=false
+SMTP_USE_STARTTLS=false
+SMTP_AUTH_REQUIRED=false
+SMTP_ALLOW_INSECURE_AUTH=false
+SMTP_FROM_ADDRESS=your-name@example.local
+SMTP_FROM_NAME=Your Name
+SMTP_TIMEOUT_SECONDS=30
+```
+
+不要把真实账号密码提交到 Git。服务日志不会打印密码。
+
+如果内网 SMTP 服务器要求在 25 端口上使用明文 SMTP AUTH，需要显式设置 `SMTP_ALLOW_INSECURE_AUTH=true`。这会把认证信息发送在未加密连接上，只应在可信内网里使用；公网服务商通常应使用 `SMTP_USE_TLS=true` 或 `SMTP_USE_STARTTLS=true`。
+
+## 启动
+
+```bash
+go run ./cmd/server
+```
+
+默认监听：
+
+```text
+http://127.0.0.1:8765
+```
+
+也可以指定配置文件：
+
+```bash
+CONFIG_PATH=/path/to/.env go run ./cmd/server
+```
+
+## 常用接口示例
+
+健康检查：
+
+```bash
+curl http://127.0.0.1:8765/health
+```
+
+从 POP3 同步邮件。同步使用 `UIDL` 去重，不默认删除服务器邮件；单封邮件失败会进入 `errors`，不会中断整次同步：
+
+```bash
+curl -X POST http://127.0.0.1:8765/sync
+```
+
+搜索本地邮件，只返回摘要：
+
+```bash
+curl "http://127.0.0.1:8765/emails/search?q=合同&from=alice@example.local&has_attachment=true&limit=20"
+```
+
+读取邮件全文：
+
+```bash
+curl http://127.0.0.1:8765/emails/1
+```
+
+读取本地线程：
+
+```bash
+curl http://127.0.0.1:8765/emails/1/thread
+```
+
+修改本地状态，不会同步回 POP3 服务器：
+
+```bash
+curl -X POST http://127.0.0.1:8765/emails/1/mark \
+  -H 'Content-Type: application/json' \
+  -d '{"read":true,"processed":true}'
+```
+
+创建标签并应用到邮件：
+
+```bash
+curl -X POST http://127.0.0.1:8765/labels \
+  -H 'Content-Type: application/json' \
+  -d '{"name":"待处理","color":"#336699"}'
+
+curl -X POST http://127.0.0.1:8765/emails/labels/apply \
+  -H 'Content-Type: application/json' \
+  -d '{"email_ids":[1],"label_ids":[1],"op":"add"}'
+```
+
+创建草稿：
+
+```bash
+curl -X POST http://127.0.0.1:8765/drafts \
+  -H 'Content-Type: application/json' \
+  -d '{"to":["bob@example.local"],"cc":[],"bcc":[],"subject":"测试","body":"你好"}'
+```
+
+列出草稿：
+
+```bash
+curl http://127.0.0.1:8765/drafts
+```
+
+修改草稿：
+
+```bash
+curl -X PATCH http://127.0.0.1:8765/drafts/1 \
+  -H 'Content-Type: application/json' \
+  -d '{"to":["bob@example.local"],"subject":"更新后的主题","body":"更新后的正文"}'
+```
+
+发送草稿。Bcc 不写入邮件头，但会参与 SMTP 实际发送；发送成功写入 `sent_messages`，回复邮件会把原邮件本地标记为 `replied=true`：
+
+```bash
+curl -X POST http://127.0.0.1:8765/drafts/1/send
+```
+
+直接发送新邮件，内部等价于创建草稿并发送：
+
+```bash
+curl -X POST http://127.0.0.1:8765/send \
+  -H 'Content-Type: application/json' \
+  -d '{"to":["bob@example.local"],"bcc":["audit@example.local"],"subject":"直接发送","body":"正文"}'
+```
+
+转发邮件。MVP 暂不转发附件，`include_attachments=true` 会返回结构化错误：
+
+```bash
+curl -X POST http://127.0.0.1:8765/emails/1/forward \
+  -H 'Content-Type: application/json' \
+  -d '{"to":["bob@example.local"],"subject":"Fwd: 原邮件","body":"请看下面原文","include_attachments":false}'
+```
+
+## 数据目录
+
+默认路径：
+
+- SQLite: `./data/internal_mail.db`
+- 原始邮件: `./data/raw`
+- 附件文件: `./data/attachments`
+
+这些运行时数据默认不提交到 Git。
+
+## 构建与测试
+
+运行测试：
+
+```bash
+go test ./...
+```
+
+只跑本地端到端测试：
+
+```bash
+go test ./internal/e2e -count=1 -v
+```
+
+`internal/e2e` 会在测试进程里启动最小 fake POP3 和 fake SMTP 服务，然后通过 HTTP API 验证：
+
+- `GET /health`
+- `POST /sync`
+- POP3 `UIDL` 去重
+- MIME 正文和附件解析
+- 附件只暴露 `attachment_id`，不暴露真实路径
+- `GET /emails/search`
+- `GET /emails/{id}`
+- 标签创建与应用
+- 本地已读、已处理、已回复状态
+- 草稿回复发送
+- `POST /send` 直接发送
+- SMTP envelope 包含 To、Cc、Bcc
+- Bcc 不写入邮件头
+- 发送成功写入 `sent_messages`
+- 发送失败写入 `sent_messages(status=failed)`，不误标记草稿为 `sent`
+
+本机编译：
+
+```bash
+go build ./cmd/server
+```
+
+交叉编译 Windows：
+
+```bash
+mkdir -p dist
+CGO_ENABLED=0 GOOS=windows GOARCH=amd64 go build -o dist/internal-mail-skill.exe ./cmd/server
+```
+
+交叉编译 Linux：
+
+```bash
+mkdir -p dist
+CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o dist/internal-mail-skill-linux-amd64 ./cmd/server
+```
+
+也可以使用 Makefile：
+
+```bash
+make test
+make e2e
+make build
+make cross-build
+```
+
+## 本地验收建议
+
+外部邮箱注册经常受风控影响，因此交接前建议先跑本地可重复验收：
+
+```bash
+go test ./internal/e2e -count=1 -v
+go test ./...
+go build ./cmd/server
+CGO_ENABLED=0 GOOS=windows GOARCH=amd64 go build -o dist/internal-mail-skill.exe ./cmd/server
+```
+
+本地 E2E 不依赖真实邮箱账号，不会发出公网邮件；它验证的是本项目对 POP3、SMTP、MIME、SQLite 和 HTTP API 的主链路处理能力。
+
+## 已完成的公网邮箱试测记录
+
+以下记录用于交接背景，不包含任何密码。
+
+- VFEmail：POP3 同步成功，SMTP 发送成功，自发自收闭环成功，邮件可通过搜索接口查到。
+- Runbox：POP3 同步成功；SMTP 587 STARTTLS 和 465 TLS 均返回 `535 Incorrect authentication data`；外部投递到该账号返回 `550 Unknown account`。
+- GMX、eclipso、Fastmail、Purelymail、mailbox.org：公开 POP3/SMTP 端口握手可达，但注册或试用受风控、手机号、试用限制影响，未形成账号级完整闭环。
+
+结论：代码主链路已用本地 E2E 和 VFEmail 真实账号闭环验证；内网交接时应重点用公司 POP3/SMTP 账号做最终验证。
+
+## 内网接手测试清单
+
+1. 复制 `.env.example` 为 `.env`，填写内网 POP3/SMTP 参数。
+2. 确认 `HTTP_HOST=127.0.0.1`，不要直接暴露到公网或共享网段。
+3. 启动服务：
+
+   ```bash
+   go run ./cmd/server
+   ```
+
+4. 健康检查：
+
+   ```bash
+   curl http://127.0.0.1:8765/health
+   ```
+
+5. 同步邮件：
+
+   ```bash
+   curl -X POST http://127.0.0.1:8765/sync
+   ```
+
+6. 再次同步，确认重复邮件进入 `skipped`，不会重复入库。
+7. 搜索一封已知邮件：
+
+   ```bash
+   curl "http://127.0.0.1:8765/emails/search?q=关键字&limit=10"
+   ```
+
+8. 读取邮件全文，确认正文、附件元数据和本地状态正常。
+9. 创建草稿并发送到测试收件人。
+10. 如果是回复邮件，确认 `In-Reply-To`、`References` 尽量写入，且原邮件本地 `replied=true`。
+11. 如果 SMTP 发出后 Webmail 的“已发送”里看不到，这是 POP3+SMTP 模式的正常限制；需要一致性时可 BCC 自己或后续接 Webmail HTTP API。
+
+## 常见问题
+
+### SMTP 25 端口能连但发不出去
+
+确认内网服务器是否需要 SMTP AUTH。如果需要明文 AUTH，必须显式设置：
+
+```dotenv
+SMTP_AUTH_REQUIRED=true
+SMTP_ALLOW_INSECURE_AUTH=true
+```
+
+公网邮箱通常不应使用明文 AUTH，应使用 `SMTP_USE_TLS=true` 或 `SMTP_USE_STARTTLS=true`。
+
+### 同步后 Webmail 里还是未读
+
+这是预期行为。POP3 无法可靠同步服务器侧已读、标签、归档、文件夹等状态；本项目只维护本地状态。
+
+### SMTP 发出的邮件没有出现在 Webmail 已发送
+
+这是预期行为。SMTP 只负责投递，不一定写入 Webmail 已发送文件夹。需要一致性时，可让系统 BCC 自己，或者后续接入 Webmail HTTP API。
+
+### 附件在哪里
+
+附件真实路径只保存在 SQLite 中，不通过 API 返回给 Agent。API 只返回 `attachment_id`、文件名、类型和大小。
--- a/cmd/server/main.go
+++ b/cmd/server/main.go
@@ -0,0 +1,97 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"log/slog"
+	"net/http"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"internal-mail-skill/internal/api"
+	"internal-mail-skill/internal/config"
+	"internal-mail-skill/internal/db"
+	"internal-mail-skill/internal/pop3"
+	"internal-mail-skill/internal/service"
+	mailsmtp "internal-mail-skill/internal/smtp"
+)
+
+func main() {
+	if err := run(); err != nil {
+		slog.Error("server stopped", "error", err)
+		os.Exit(1)
+	}
+}
+
+func run() error {
+	cfgPath := os.Getenv("CONFIG_PATH")
+	if cfgPath == "" {
+		cfgPath = ".env"
+	}
+	cfg, err := config.Load(cfgPath)
+	if err != nil {
+		return err
+	}
+	if err := ensureDataDirs(cfg); err != nil {
+		return err
+	}
+
+	store, err := db.Open(cfg.Data.DatabasePath)
+	if err != nil {
+		return err
+	}
+	defer store.Close()
+
+	ctx := context.Background()
+	if err := store.Migrate(ctx); err != nil {
+		return err
+	}
+
+	popFetcher := pop3.NewFetcher(cfg.POP3)
+	smtpSender := mailsmtp.NewSender(cfg.SMTP)
+	mailService := service.NewWithOptions(store, popFetcher, smtpSender, cfg.AccountID, service.Options{
+		RawDir:        cfg.Data.RawMailDir,
+		AttachmentDir: cfg.Data.AttachmentDir,
+		FromAddress:   cfg.SMTP.FromAddress,
+		FromName:      cfg.SMTP.FromName,
+	})
+	apiServer := api.New(cfg, store, mailService)
+
+	httpServer := &http.Server{
+		Addr:              api.ListenAddr(cfg),
+		Handler:           apiServer.Handler(),
+		ReadHeaderTimeout: 10 * time.Second,
+	}
+
+	errCh := make(chan error, 1)
+	go func() {
+		slog.Info("internal mail skill listening", "addr", httpServer.Addr, "account_id", cfg.AccountID)
+		errCh <- httpServer.ListenAndServe()
+	}()
+
+	stopCh := make(chan os.Signal, 1)
+	signal.Notify(stopCh, syscall.SIGINT, syscall.SIGTERM)
+	select {
+	case sig := <-stopCh:
+		slog.Info("shutdown requested", "signal", sig.String())
+		shutdownCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cancel()
+		return httpServer.Shutdown(shutdownCtx)
+	case err := <-errCh:
+		if errors.Is(err, http.ErrServerClosed) {
+			return nil
+		}
+		return err
+	}
+}
+
+func ensureDataDirs(cfg *config.Config) error {
+	for _, dir := range []string{cfg.Data.DataDir, cfg.Data.RawMailDir, cfg.Data.AttachmentDir} {
+		if err := os.MkdirAll(dir, 0750); err != nil {
+			return err
+		}
+	}
+	return nil
+}
--- a/data/.gitkeep
+++ b/data/.gitkeep
@@ -0,0 +1 @@
+
--- a/go.mod
+++ b/go.mod
@@ -0,0 +1,24 @@
+module internal-mail-skill
+
+go 1.24.0
+
+require (
+	github.com/knadh/go-pop3 v1.0.2
+	golang.org/x/net v0.47.0
+	modernc.org/sqlite v1.40.1
+)
+
+require (
+	github.com/dustin/go-humanize v1.0.1 // indirect
+	github.com/emersion/go-message v0.18.2 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/ncruces/go-strftime v0.1.9 // indirect
+	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
+	golang.org/x/exp v0.0.0-20250620022241-b7579e27df2b // indirect
+	golang.org/x/sys v0.38.0 // indirect
+	golang.org/x/text v0.31.0 // indirect
+	modernc.org/libc v1.66.10 // indirect
+	modernc.org/mathutil v1.7.1 // indirect
+	modernc.org/memory v1.11.0 // indirect
+)
--- a/go.sum
+++ b/go.sum
@@ -0,0 +1,88 @@
+github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
+github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
+github.com/emersion/go-message v0.18.2 h1:rl55SQdjd9oJcIoQNhubD2Acs1E6IzlZISRTK7x/Lpg=
+github.com/emersion/go-message v0.18.2/go.mod h1:XpJyL70LwRvq2a8rVbHXikPgKj8+aI0kGdHlg16ibYA=
+github.com/google/pprof v0.0.0-20250317173921-a4b03ec1a45e h1:ijClszYn+mADRFY17kjQEVQ1XRhq2/JR1M3sGqeJoxs=
+github.com/google/pprof v0.0.0-20250317173921-a4b03ec1a45e/go.mod h1:boTsfXsheKC2y+lKOCMpSfarhxDeIzfZG1jqGcPl3cA=
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/knadh/go-pop3 v1.0.2 h1:gbdtwzEYedLVos/vpebM2d73NTyZxEgjgRJ4S77HlzM=
+github.com/knadh/go-pop3 v1.0.2/go.mod h1:3gKw2jmrEa1lYLVtP1yEoo6bkkJ4XHDySPy8xaSjG0s=
+github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
+github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
+github.com/ncruces/go-strftime v0.1.9 h1:bY0MQC28UADQmHmaF5dgpLmImcShSi2kHU9XLdhx/f4=
+github.com/ncruces/go-strftime v0.1.9/go.mod h1:Fwc5htZGVVkseilnfgOVb9mKy6w1naJmn9CehxcKcls=
+github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec h1:W09IVJc94icq4NjY3clb7Lk8O1qJ8BdBEF8z0ibU0rE=
+github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec/go.mod h1:qqbHyh8v60DhA7CoWK5oRCqLrMHRGoxYCSS9EjAz6Eo=
+github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/exp v0.0.0-20250620022241-b7579e27df2b h1:M2rDM6z3Fhozi9O7NWsxAkg/yqS/lQJ6PmkyIV3YP+o=
+golang.org/x/exp v0.0.0-20250620022241-b7579e27df2b/go.mod h1:3//PLf8L/X+8b4vuAfHzxeRUl04Adcb341+IGKfnqS8=
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+modernc.org/token v1.1.0/go.mod h1:UGzOrNV1mAFSEB63lOFHIpNRUVMvYTc6yu1SMY/XTDM=
--- a/internal/api/api.go
+++ b/internal/api/api.go
@@ -0,0 +1,331 @@
+package api
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"strconv"
+	"time"
+
+	"internal-mail-skill/internal/config"
+	"internal-mail-skill/internal/db"
+	"internal-mail-skill/internal/service"
+)
+
+const Version = "0.1.0"
+
+type Server struct {
+	cfg   *config.Config
+	store *db.Store
+	svc   *service.Service
+}
+
+func New(cfg *config.Config, store *db.Store, svc *service.Service) *Server {
+	return &Server{cfg: cfg, store: store, svc: svc}
+}
+
+func (s *Server) Handler() http.Handler {
+	mux := http.NewServeMux()
+	mux.HandleFunc("GET /health", s.health)
+	mux.HandleFunc("POST /sync", s.sync)
+	mux.HandleFunc("GET /emails/search", s.searchEmails)
+	mux.HandleFunc("GET /emails/{id}", s.getEmail)
+	mux.HandleFunc("GET /emails/{id}/thread", s.getThread)
+	mux.HandleFunc("POST /emails/{id}/mark", s.markEmail)
+	mux.HandleFunc("POST /labels", s.createLabel)
+	mux.HandleFunc("POST /emails/labels/apply", s.applyLabels)
+	mux.HandleFunc("POST /drafts", s.createDraft)
+	mux.HandleFunc("GET /drafts", s.listDrafts)
+	mux.HandleFunc("PATCH /drafts/{id}", s.updateDraft)
+	mux.HandleFunc("POST /drafts/{id}/send", s.sendDraft)
+	mux.HandleFunc("POST /send", s.sendDirect)
+	mux.HandleFunc("POST /emails/{id}/forward", s.forwardEmail)
+	return withJSON(mux)
+}
+
+func (s *Server) health(w http.ResponseWriter, r *http.Request) {
+	dbStatus := "ok"
+	if err := s.store.Ping(r.Context()); err != nil {
+		dbStatus = "down"
+	}
+	writeJSON(w, http.StatusOK, map[string]any{
+		"status":     dbStatus,
+		"version":    Version,
+		"database":   dbStatus,
+		"account_id": s.cfg.AccountID,
+		"time":       time.Now().UTC().Format(time.RFC3339),
+	})
+}
+
+func (s *Server) sync(w http.ResponseWriter, r *http.Request) {
+	result, err := s.svc.Sync(r.Context())
+	if err != nil {
+		writeError(w, http.StatusBadGateway, "sync_failed", err.Error(), nil)
+		return
+	}
+	writeJSON(w, http.StatusOK, result)
+}
+
+func (s *Server) searchEmails(w http.ResponseWriter, r *http.Request) {
+	q := r.URL.Query()
+	filters := service.SearchFilters{
+		Q:      q.Get("q"),
+		From:   q.Get("from"),
+		To:     q.Get("to"),
+		After:  q.Get("after"),
+		Before: q.Get("before"),
+		Limit:  intQuery(q.Get("limit"), 50),
+		Offset: intQuery(q.Get("offset"), 0),
+	}
+	filters.HasAttachment = boolQuery(q.Get("has_attachment"))
+	filters.Read = boolQuery(q.Get("read"))
+	filters.Processed = boolQuery(q.Get("processed"))
+	filters.Archived = boolQuery(q.Get("archived"))
+	filters.Replied = boolQuery(q.Get("replied"))
+	results, err := s.svc.SearchEmails(r.Context(), filters)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "search_failed", err.Error(), nil)
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"emails": results, "limit": filters.Limit, "offset": filters.Offset})
+}
+
+func (s *Server) getEmail(w http.ResponseWriter, r *http.Request) {
+	id, ok := pathID(w, r)
+	if !ok {
+		return
+	}
+	email, err := s.svc.GetEmail(r.Context(), id)
+	if err != nil {
+		handleServiceError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, email)
+}
+
+func (s *Server) getThread(w http.ResponseWriter, r *http.Request) {
+	id, ok := pathID(w, r)
+	if !ok {
+		return
+	}
+	thread, err := s.svc.GetThread(r.Context(), id)
+	if err != nil {
+		handleServiceError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"thread": thread})
+}
+
+func (s *Server) markEmail(w http.ResponseWriter, r *http.Request) {
+	id, ok := pathID(w, r)
+	if !ok {
+		return
+	}
+	var input service.MarkInput
+	if !decodeBody(w, r, &input) {
+		return
+	}
+	if err := s.svc.MarkEmail(r.Context(), id, input); err != nil {
+		handleServiceError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"ok": true})
+}
+
+func (s *Server) createLabel(w http.ResponseWriter, r *http.Request) {
+	var input struct {
+		Name  string `json:"name"`
+		Color string `json:"color"`
+	}
+	if !decodeBody(w, r, &input) {
+		return
+	}
+	label, err := s.svc.CreateLabel(r.Context(), input.Name, input.Color)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "label_failed", err.Error(), nil)
+		return
+	}
+	writeJSON(w, http.StatusCreated, label)
+}
+
+func (s *Server) applyLabels(w http.ResponseWriter, r *http.Request) {
+	var input struct {
+		EmailIDs []int64 `json:"email_ids"`
+		LabelIDs []int64 `json:"label_ids"`
+		Op       string  `json:"op"`
+	}
+	if !decodeBody(w, r, &input) {
+		return
+	}
+	if err := s.svc.ApplyLabels(r.Context(), input.EmailIDs, input.LabelIDs, input.Op); err != nil {
+		writeError(w, http.StatusBadRequest, "label_apply_failed", err.Error(), nil)
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"ok": true})
+}
+
+func (s *Server) createDraft(w http.ResponseWriter, r *http.Request) {
+	var input service.DraftInput
+	if !decodeBody(w, r, &input) {
+		return
+	}
+	draft, err := s.svc.CreateDraft(r.Context(), input)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "draft_create_failed", err.Error(), nil)
+		return
+	}
+	writeJSON(w, http.StatusCreated, draft)
+}
+
+func (s *Server) listDrafts(w http.ResponseWriter, r *http.Request) {
+	drafts, err := s.svc.ListDrafts(r.Context())
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "draft_list_failed", err.Error(), nil)
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"drafts": drafts})
+}
+
+func (s *Server) updateDraft(w http.ResponseWriter, r *http.Request) {
+	id, ok := pathID(w, r)
+	if !ok {
+		return
+	}
+	var input service.DraftInput
+	if !decodeBody(w, r, &input) {
+		return
+	}
+	draft, err := s.svc.UpdateDraft(r.Context(), id, input)
+	if err != nil {
+		handleServiceError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, draft)
+}
+
+func (s *Server) sendDraft(w http.ResponseWriter, r *http.Request) {
+	id, ok := pathID(w, r)
+	if !ok {
+		return
+	}
+	outcome, err := s.svc.SendDraft(r.Context(), id)
+	if err != nil {
+		writeError(w, http.StatusBadGateway, "send_failed", err.Error(), outcome)
+		return
+	}
+	writeJSON(w, http.StatusOK, outcome)
+}
+
+func (s *Server) sendDirect(w http.ResponseWriter, r *http.Request) {
+	var input service.DraftInput
+	if !decodeBody(w, r, &input) {
+		return
+	}
+	outcome, err := s.svc.SendDirect(r.Context(), input)
+	if err != nil {
+		writeError(w, http.StatusBadGateway, "send_failed", err.Error(), outcome)
+		return
+	}
+	writeJSON(w, http.StatusOK, outcome)
+}
+
+func (s *Server) forwardEmail(w http.ResponseWriter, r *http.Request) {
+	id, ok := pathID(w, r)
+	if !ok {
+		return
+	}
+	var input service.ForwardInput
+	if !decodeBody(w, r, &input) {
+		return
+	}
+	outcome, err := s.svc.ForwardEmail(r.Context(), id, input)
+	if err != nil {
+		handleServiceError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, outcome)
+}
+
+func decodeBody(w http.ResponseWriter, r *http.Request, dst any) bool {
+	defer r.Body.Close()
+	if err := json.NewDecoder(r.Body).Decode(dst); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid_json", err.Error(), nil)
+		return false
+	}
+	return true
+}
+
+func pathID(w http.ResponseWriter, r *http.Request) (int64, bool) {
+	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
+	if err != nil || id <= 0 {
+		writeError(w, http.StatusBadRequest, "invalid_id", "id must be a positive integer", nil)
+		return 0, false
+	}
+	return id, true
+}
+
+func intQuery(value string, def int) int {
+	if value == "" {
+		return def
+	}
+	n, err := strconv.Atoi(value)
+	if err != nil {
+		return def
+	}
+	return n
+}
+
+func boolQuery(value string) *bool {
+	if value == "" {
+		return nil
+	}
+	switch value {
+	case "1", "true", "TRUE", "yes", "on":
+		v := true
+		return &v
+	case "0", "false", "FALSE", "no", "off":
+		v := false
+		return &v
+	default:
+		return nil
+	}
+}
+
+func handleServiceError(w http.ResponseWriter, err error) {
+	switch {
+	case errors.Is(err, service.ErrNotFound):
+		writeError(w, http.StatusNotFound, "not_found", err.Error(), nil)
+	case errors.Is(err, service.ErrAttachmentsForwardUnsupported):
+		writeError(w, http.StatusBadRequest, "attachments_forward_unsupported", err.Error(), nil)
+	default:
+		writeError(w, http.StatusInternalServerError, "internal_error", err.Error(), nil)
+	}
+}
+
+func writeJSON(w http.ResponseWriter, status int, payload any) {
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.WriteHeader(status)
+	_ = json.NewEncoder(w).Encode(payload)
+}
+
+func writeError(w http.ResponseWriter, status int, code, message string, details any) {
+	writeJSON(w, status, map[string]any{
+		"error": map[string]any{
+			"code":    code,
+			"message": message,
+			"details": details,
+		},
+	})
+}
+
+func withJSON(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("X-Content-Type-Options", "nosniff")
+		next.ServeHTTP(w, r)
+	})
+}
+
+func ListenAddr(cfg *config.Config) string {
+	return fmt.Sprintf("%s:%d", cfg.HTTP.Host, cfg.HTTP.Port)
+}
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -0,0 +1,177 @@
+package config
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+)
+
+type Config struct {
+	AccountID string
+	POP3      POP3Config
+	SMTP      SMTPConfig
+	Data      DataConfig
+	HTTP      HTTPConfig
+}
+
+type POP3Config struct {
+	Host           string
+	Port           int
+	Username       string
+	Password       string
+	UseTLS         bool
+	TimeoutSeconds int
+}
+
+type SMTPConfig struct {
+	Host              string
+	Port              int
+	Username          string
+	Password          string
+	UseTLS            bool
+	UseSTARTTLS       bool
+	AuthRequired      bool
+	AllowInsecureAuth bool
+	FromAddress       string
+	FromName          string
+	TimeoutSeconds    int
+}
+
+type DataConfig struct {
+	DataDir       string
+	DatabasePath  string
+	RawMailDir    string
+	AttachmentDir string
+}
+
+type HTTPConfig struct {
+	Host string
+	Port int
+}
+
+func (c POP3Config) Timeout() time.Duration {
+	return time.Duration(c.TimeoutSeconds) * time.Second
+}
+
+func (c SMTPConfig) Timeout() time.Duration {
+	return time.Duration(c.TimeoutSeconds) * time.Second
+}
+
+func Load(envPath string) (*Config, error) {
+	values := map[string]string{}
+	if envPath == "" {
+		envPath = ".env"
+	}
+	if err := readEnvFile(envPath, values); err != nil {
+		return nil, err
+	}
+	for _, item := range os.Environ() {
+		key, val, ok := strings.Cut(item, "=")
+		if ok {
+			values[key] = val
+		}
+	}
+
+	dataDir := getString(values, "DATA_DIR", "./data")
+	cfg := &Config{
+		AccountID: getString(values, "MAIL_ACCOUNT_ID", "default"),
+		POP3: POP3Config{
+			Host:           getString(values, "POP3_HOST", ""),
+			Port:           getInt(values, "POP3_PORT", 110),
+			Username:       getString(values, "POP3_USERNAME", ""),
+			Password:       getString(values, "POP3_PASSWORD", ""),
+			UseTLS:         getBool(values, "POP3_USE_TLS", false),
+			TimeoutSeconds: getInt(values, "POP3_TIMEOUT_SECONDS", 30),
+		},
+		SMTP: SMTPConfig{
+			Host:              getString(values, "SMTP_HOST", ""),
+			Port:              getInt(values, "SMTP_PORT", 25),
+			Username:          getString(values, "SMTP_USERNAME", ""),
+			Password:          getString(values, "SMTP_PASSWORD", ""),
+			UseTLS:            getBool(values, "SMTP_USE_TLS", false),
+			UseSTARTTLS:       getBool(values, "SMTP_USE_STARTTLS", false),
+			AuthRequired:      getBool(values, "SMTP_AUTH_REQUIRED", false),
+			AllowInsecureAuth: getBool(values, "SMTP_ALLOW_INSECURE_AUTH", false),
+			FromAddress:       getString(values, "SMTP_FROM_ADDRESS", ""),
+			FromName:          getString(values, "SMTP_FROM_NAME", ""),
+			TimeoutSeconds:    getInt(values, "SMTP_TIMEOUT_SECONDS", 30),
+		},
+		Data: DataConfig{
+			DataDir:       dataDir,
+			DatabasePath:  getString(values, "DATABASE_PATH", filepath.Join(dataDir, "internal_mail.db")),
+			RawMailDir:    getString(values, "RAW_MAIL_DIR", filepath.Join(dataDir, "raw")),
+			AttachmentDir: getString(values, "ATTACHMENT_DIR", filepath.Join(dataDir, "attachments")),
+		},
+		HTTP: HTTPConfig{
+			Host: getString(values, "HTTP_HOST", "127.0.0.1"),
+			Port: getInt(values, "HTTP_PORT", 8765),
+		},
+	}
+	return cfg, nil
+}
+
+func readEnvFile(path string, values map[string]string) error {
+	file, err := os.Open(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return fmt.Errorf("read env file: %w", err)
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		if line == "" || strings.HasPrefix(line, "#") {
+			continue
+		}
+		key, value, ok := strings.Cut(line, "=")
+		if !ok {
+			continue
+		}
+		key = strings.TrimSpace(key)
+		value = strings.TrimSpace(value)
+		value = strings.Trim(value, `"'`)
+		values[key] = value
+	}
+	return scanner.Err()
+}
+
+func getString(values map[string]string, key, def string) string {
+	if v, ok := values[key]; ok {
+		return v
+	}
+	return def
+}
+
+func getInt(values map[string]string, key string, def int) int {
+	v, ok := values[key]
+	if !ok || strings.TrimSpace(v) == "" {
+		return def
+	}
+	n, err := strconv.Atoi(v)
+	if err != nil {
+		return def
+	}
+	return n
+}
+
+func getBool(values map[string]string, key string, def bool) bool {
+	v, ok := values[key]
+	if !ok || strings.TrimSpace(v) == "" {
+		return def
+	}
+	switch strings.ToLower(strings.TrimSpace(v)) {
+	case "1", "true", "yes", "y", "on":
+		return true
+	case "0", "false", "no", "n", "off":
+		return false
+	default:
+		return def
+	}
+}
--- a/internal/config/config_test.go
+++ b/internal/config/config_test.go
@@ -0,0 +1,42 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestLoadDefaultsAndEnvFile(t *testing.T) {
+	dir := t.TempDir()
+	envPath := filepath.Join(dir, ".env")
+	if err := os.WriteFile(envPath, []byte("POP3_HOST=mail.local\nSMTP_PORT=2525\nSMTP_AUTH_REQUIRED=true\nSMTP_ALLOW_INSECURE_AUTH=true\nDATA_DIR="+dir+"\n"), 0600); err != nil {
+		t.Fatal(err)
+	}
+
+	cfg, err := Load(envPath)
+	if err != nil {
+		t.Fatalf("Load() error = %v", err)
+	}
+
+	if cfg.AccountID != "default" {
+		t.Fatalf("AccountID = %q, want default", cfg.AccountID)
+	}
+	if cfg.POP3.Host != "mail.local" {
+		t.Fatalf("POP3.Host = %q", cfg.POP3.Host)
+	}
+	if cfg.POP3.Port != 110 {
+		t.Fatalf("POP3.Port = %d, want 110", cfg.POP3.Port)
+	}
+	if cfg.SMTP.Port != 2525 {
+		t.Fatalf("SMTP.Port = %d, want 2525", cfg.SMTP.Port)
+	}
+	if !cfg.SMTP.AuthRequired {
+		t.Fatal("SMTP.AuthRequired = false, want true")
+	}
+	if !cfg.SMTP.AllowInsecureAuth {
+		t.Fatal("SMTP.AllowInsecureAuth = false, want true")
+	}
+	if cfg.HTTP.Host != "127.0.0.1" || cfg.HTTP.Port != 8765 {
+		t.Fatalf("HTTP default = %s:%d", cfg.HTTP.Host, cfg.HTTP.Port)
+	}
+}
--- a/internal/db/db.go
+++ b/internal/db/db.go
@@ -0,0 +1,164 @@
+package db
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	_ "modernc.org/sqlite"
+)
+
+type Store struct {
+	DB *sql.DB
+}
+
+func Open(path string) (*Store, error) {
+	if path != ":memory:" {
+		if err := os.MkdirAll(filepath.Dir(path), 0750); err != nil {
+			return nil, fmt.Errorf("create database directory: %w", err)
+		}
+	}
+	db, err := sql.Open("sqlite", path)
+	if err != nil {
+		return nil, fmt.Errorf("open sqlite: %w", err)
+	}
+	if _, err := db.Exec("PRAGMA foreign_keys = ON"); err != nil {
+		_ = db.Close()
+		return nil, fmt.Errorf("enable foreign keys: %w", err)
+	}
+	if path == ":memory:" {
+		db.SetMaxOpenConns(1)
+	}
+	return &Store{DB: db}, nil
+}
+
+func (s *Store) Close() error {
+	if s == nil || s.DB == nil {
+		return nil
+	}
+	return s.DB.Close()
+}
+
+func (s *Store) Ping(ctx context.Context) error {
+	return s.DB.PingContext(ctx)
+}
+
+func (s *Store) Migrate(ctx context.Context) error {
+	_, err := s.DB.ExecContext(ctx, schemaSQL)
+	if err != nil {
+		return fmt.Errorf("migrate sqlite: %w", err)
+	}
+	return nil
+}
+
+const schemaSQL = `
+CREATE TABLE IF NOT EXISTS mail_messages (
+	id INTEGER PRIMARY KEY AUTOINCREMENT,
+	account_id TEXT NOT NULL,
+	pop3_uid TEXT NOT NULL,
+	message_id_header TEXT,
+	in_reply_to TEXT,
+	references_header TEXT,
+	subject TEXT,
+	sender_name TEXT,
+	sender_email TEXT,
+	to_json TEXT NOT NULL DEFAULT '[]',
+	cc_json TEXT NOT NULL DEFAULT '[]',
+	date_header TEXT,
+	sent_at TEXT,
+	received_at TEXT NOT NULL,
+	body_text TEXT,
+	body_html TEXT,
+	raw_eml_path TEXT,
+	has_attachment INTEGER NOT NULL DEFAULT 0,
+	local_read INTEGER NOT NULL DEFAULT 0,
+	local_processed INTEGER NOT NULL DEFAULT 0,
+	local_archived INTEGER NOT NULL DEFAULT 0,
+	local_deleted INTEGER NOT NULL DEFAULT 0,
+	local_replied INTEGER NOT NULL DEFAULT 0,
+	created_at TEXT NOT NULL,
+	updated_at TEXT NOT NULL,
+	UNIQUE(account_id, pop3_uid)
+);
+
+CREATE INDEX IF NOT EXISTS idx_mail_messages_account_uid ON mail_messages(account_id, pop3_uid);
+CREATE INDEX IF NOT EXISTS idx_mail_messages_message_id ON mail_messages(message_id_header);
+CREATE INDEX IF NOT EXISTS idx_mail_messages_sender ON mail_messages(sender_email);
+CREATE INDEX IF NOT EXISTS idx_mail_messages_sent_at ON mail_messages(sent_at);
+CREATE INDEX IF NOT EXISTS idx_mail_messages_status ON mail_messages(local_read, local_processed, local_archived, local_deleted, local_replied);
+
+CREATE TABLE IF NOT EXISTS attachments (
+	id INTEGER PRIMARY KEY AUTOINCREMENT,
+	message_id INTEGER NOT NULL,
+	file_name TEXT NOT NULL,
+	content_type TEXT,
+	content_id TEXT,
+	size_bytes INTEGER NOT NULL DEFAULT 0,
+	storage_path TEXT NOT NULL,
+	created_at TEXT NOT NULL,
+	FOREIGN KEY(message_id) REFERENCES mail_messages(id) ON DELETE CASCADE
+);
+
+CREATE INDEX IF NOT EXISTS idx_attachments_message ON attachments(message_id);
+
+CREATE TABLE IF NOT EXISTS labels (
+	id INTEGER PRIMARY KEY AUTOINCREMENT,
+	name TEXT NOT NULL UNIQUE,
+	color TEXT,
+	created_at TEXT NOT NULL,
+	updated_at TEXT NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS message_labels (
+	message_id INTEGER NOT NULL,
+	label_id INTEGER NOT NULL,
+	created_at TEXT NOT NULL,
+	PRIMARY KEY(message_id, label_id),
+	FOREIGN KEY(message_id) REFERENCES mail_messages(id) ON DELETE CASCADE,
+	FOREIGN KEY(label_id) REFERENCES labels(id) ON DELETE CASCADE
+);
+
+CREATE INDEX IF NOT EXISTS idx_message_labels_label ON message_labels(label_id);
+
+CREATE TABLE IF NOT EXISTS drafts (
+	id INTEGER PRIMARY KEY AUTOINCREMENT,
+	to_json TEXT NOT NULL DEFAULT '[]',
+	cc_json TEXT NOT NULL DEFAULT '[]',
+	bcc_json TEXT NOT NULL DEFAULT '[]',
+	subject TEXT,
+	body TEXT,
+	reply_to_email_id INTEGER,
+	status TEXT NOT NULL DEFAULT 'draft',
+	last_error TEXT,
+	sent_message_id INTEGER,
+	created_at TEXT NOT NULL,
+	updated_at TEXT NOT NULL,
+	FOREIGN KEY(reply_to_email_id) REFERENCES mail_messages(id) ON DELETE SET NULL
+);
+
+CREATE INDEX IF NOT EXISTS idx_drafts_status ON drafts(status);
+
+CREATE TABLE IF NOT EXISTS sent_messages (
+	id INTEGER PRIMARY KEY AUTOINCREMENT,
+	draft_id INTEGER,
+	to_json TEXT NOT NULL DEFAULT '[]',
+	cc_json TEXT NOT NULL DEFAULT '[]',
+	bcc_json TEXT NOT NULL DEFAULT '[]',
+	subject TEXT,
+	body TEXT,
+	message_id_header TEXT,
+	in_reply_to TEXT,
+	references_header TEXT,
+	smtp_from TEXT,
+	status TEXT NOT NULL,
+	error_message TEXT,
+	sent_at TEXT,
+	created_at TEXT NOT NULL,
+	FOREIGN KEY(draft_id) REFERENCES drafts(id) ON DELETE SET NULL
+);
+
+CREATE INDEX IF NOT EXISTS idx_sent_messages_draft ON sent_messages(draft_id);
+CREATE INDEX IF NOT EXISTS idx_sent_messages_status ON sent_messages(status);
+`
--- a/internal/db/db_test.go
+++ b/internal/db/db_test.go
@@ -0,0 +1,33 @@
+package db
+
+import (
+	"context"
+	"database/sql"
+	"testing"
+)
+
+func TestOpenAndMigrateCreatesCoreTables(t *testing.T) {
+	store, err := Open(":memory:")
+	if err != nil {
+		t.Fatalf("Open() error = %v", err)
+	}
+	defer store.Close()
+
+	if err := store.Migrate(context.Background()); err != nil {
+		t.Fatalf("Migrate() error = %v", err)
+	}
+
+	var name string
+	err = store.DB.QueryRowContext(context.Background(), "SELECT name FROM sqlite_master WHERE type='table' AND name='mail_messages'").Scan(&name)
+	if err != nil {
+		t.Fatalf("mail_messages table missing: %v", err)
+	}
+
+	err = store.DB.QueryRowContext(context.Background(), "SELECT name FROM sqlite_master WHERE type='table' AND name='sent_messages'").Scan(&name)
+	if err != nil && err != sql.ErrNoRows {
+		t.Fatalf("sent_messages lookup failed: %v", err)
+	}
+	if name != "sent_messages" {
+		t.Fatalf("sent_messages table missing, got %q", name)
+	}
+}
--- a/internal/e2e/local_e2e_test.go
+++ b/internal/e2e/local_e2e_test.go
@@ -0,0 +1,571 @@
+package e2e
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"mime/multipart"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"net/textproto"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"internal-mail-skill/internal/api"
+	"internal-mail-skill/internal/config"
+	"internal-mail-skill/internal/db"
+	"internal-mail-skill/internal/pop3"
+	"internal-mail-skill/internal/service"
+	mailsmtp "internal-mail-skill/internal/smtp"
+)
+
+func TestLocalPOP3SMTPHTTPFlow(t *testing.T) {
+	ctx := context.Background()
+	now := time.Date(2026, 6, 6, 9, 30, 0, 0, time.UTC)
+	raw := buildTestMessage(t, now)
+	popServer := newFakePOP3Server(t, []popMessage{{uid: "uid-local-1", raw: raw}})
+	smtpServer := newFakeSMTPServer(t)
+
+	dataDir := t.TempDir()
+	store, err := db.Open(filepath.Join(dataDir, "mail.db"))
+	if err != nil {
+		t.Fatalf("open db: %v", err)
+	}
+	t.Cleanup(func() { _ = store.Close() })
+	if err := store.Migrate(ctx); err != nil {
+		t.Fatalf("migrate db: %v", err)
+	}
+
+	cfg := &config.Config{
+		AccountID: "local-e2e",
+		POP3: config.POP3Config{
+			Host:           popServer.host,
+			Port:           popServer.port,
+			Username:       "local-user",
+			Password:       "local-pass",
+			TimeoutSeconds: 5,
+		},
+		SMTP: config.SMTPConfig{
+			Host:              smtpServer.host,
+			Port:              smtpServer.port,
+			FromAddress:       "agent@example.local",
+			FromName:          "Local Agent",
+			TimeoutSeconds:    5,
+			AuthRequired:      true,
+			Username:          "smtp-user",
+			Password:          "smtp-pass",
+			AllowInsecureAuth: true,
+		},
+		Data: config.DataConfig{
+			DataDir:       dataDir,
+			DatabasePath:  filepath.Join(dataDir, "mail.db"),
+			RawMailDir:    filepath.Join(dataDir, "raw"),
+			AttachmentDir: filepath.Join(dataDir, "attachments"),
+		},
+	}
+	svc := service.NewWithOptions(
+		store,
+		pop3.NewFetcher(cfg.POP3),
+		mailsmtp.NewSender(cfg.SMTP),
+		cfg.AccountID,
+		service.Options{RawDir: cfg.Data.RawMailDir, AttachmentDir: cfg.Data.AttachmentDir, FromAddress: cfg.SMTP.FromAddress, FromName: cfg.SMTP.FromName},
+	)
+	server := httptest.NewServer(api.New(cfg, store, svc).Handler())
+	t.Cleanup(server.Close)
+
+	health := getJSON[map[string]any](t, server.URL+"/health")
+	if health["status"] != "ok" || health["database"] != "ok" {
+		t.Fatalf("unexpected health: %#v", health)
+	}
+
+	syncResult := postJSON[map[string]any](t, server.URL+"/sync", nil, http.StatusOK)
+	if got := int(syncResult["stored"].(float64)); got != 1 {
+		t.Fatalf("stored = %d, want 1; result=%#v", got, syncResult)
+	}
+	syncAgain := postJSON[map[string]any](t, server.URL+"/sync", nil, http.StatusOK)
+	if got := int(syncAgain["skipped"].(float64)); got != 1 {
+		t.Fatalf("skipped after second sync = %d, want 1; result=%#v", got, syncAgain)
+	}
+
+	search := getJSON[map[string]any](t, server.URL+"/emails/search?q=Quarterly+Report&has_attachment=true")
+	emails := search["emails"].([]any)
+	if len(emails) != 1 {
+		t.Fatalf("search returned %d emails, want 1: %#v", len(emails), search)
+	}
+	emailID := int64(emails[0].(map[string]any)["id"].(float64))
+
+	detail := getJSON[map[string]any](t, fmt.Sprintf("%s/emails/%d", server.URL, emailID))
+	if detail["subject"] != "Quarterly Report" {
+		t.Fatalf("subject = %q", detail["subject"])
+	}
+	if !strings.Contains(detail["body_text"].(string), "The report is attached.") {
+		t.Fatalf("body_text missing expected content: %q", detail["body_text"])
+	}
+	attachments := detail["attachments"].([]any)
+	if len(attachments) != 1 {
+		t.Fatalf("attachments = %d, want 1", len(attachments))
+	}
+	if _, ok := attachments[0].(map[string]any)["attachment_id"]; !ok {
+		t.Fatalf("attachment id not exposed in detail: %#v", attachments[0])
+	}
+	if _, ok := attachments[0].(map[string]any)["storage_path"]; ok {
+		t.Fatalf("attachment storage path leaked: %#v", attachments[0])
+	}
+
+	label := postJSON[map[string]any](t, server.URL+"/labels", map[string]any{"name": "Local E2E", "color": "#336699"}, http.StatusCreated)
+	postJSON[map[string]any](t, server.URL+"/emails/labels/apply", map[string]any{
+		"email_ids": []int64{emailID},
+		"label_ids": []int64{int64(label["id"].(float64))},
+		"op":        "add",
+	}, http.StatusOK)
+	postJSON[map[string]any](t, fmt.Sprintf("%s/emails/%d/mark", server.URL, emailID), map[string]any{"read": true, "processed": true}, http.StatusOK)
+
+	marked := getJSON[map[string]any](t, fmt.Sprintf("%s/emails/%d", server.URL, emailID))
+	status := marked["local_status"].(map[string]any)
+	if status["read"] != true || status["processed"] != true {
+		t.Fatalf("local status not updated: %#v", status)
+	}
+	if got := len(marked["labels"].([]any)); got != 1 {
+		t.Fatalf("labels after apply = %d, want 1", got)
+	}
+
+	draft := postJSON[map[string]any](t, server.URL+"/drafts", map[string]any{
+		"to":                []string{"recipient@example.local"},
+		"cc":                []string{"copy@example.local"},
+		"bcc":               []string{"audit@example.local"},
+		"subject":           "Re: Quarterly Report",
+		"body":              "Thanks, received.",
+		"reply_to_email_id": emailID,
+	}, http.StatusCreated)
+	outcome := postJSON[map[string]any](t, fmt.Sprintf("%s/drafts/%d/send", server.URL, int64(draft["id"].(float64))), nil, http.StatusOK)
+	if sent := outcome["sent_message"].(map[string]any); sent["status"] != "sent" {
+		t.Fatalf("draft send status = %#v", sent)
+	}
+
+	sentMessages := smtpServer.messages()
+	if len(sentMessages) != 1 {
+		t.Fatalf("smtp captured %d messages, want 1", len(sentMessages))
+	}
+	if !containsAll(sentMessages[0].recipients, []string{"recipient@example.local", "copy@example.local", "audit@example.local"}) {
+		t.Fatalf("smtp recipients = %#v", sentMessages[0].recipients)
+	}
+	rawSent := string(sentMessages[0].data)
+	if strings.Contains(rawSent, "audit@example.local") {
+		t.Fatalf("Bcc recipient leaked into message headers/body:\n%s", rawSent)
+	}
+	if !strings.Contains(rawSent, "In-Reply-To: <local-1@example.local>") {
+		t.Fatalf("reply headers missing from SMTP message:\n%s", rawSent)
+	}
+
+	replied := getJSON[map[string]any](t, fmt.Sprintf("%s/emails/%d", server.URL, emailID))
+	if replied["local_status"].(map[string]any)["replied"] != true {
+		t.Fatalf("original message was not marked replied: %#v", replied["local_status"])
+	}
+
+	postJSON[map[string]any](t, server.URL+"/send", map[string]any{
+		"to":      []string{"new@example.local"},
+		"subject": "Direct local send",
+		"body":    "Hello from direct send.",
+	}, http.StatusOK)
+	if len(smtpServer.messages()) != 2 {
+		t.Fatalf("smtp captured %d messages after /send, want 2", len(smtpServer.messages()))
+	}
+
+	var sentCount int
+	if err := store.DB.QueryRowContext(ctx, "SELECT COUNT(*) FROM sent_messages WHERE status = 'sent'").Scan(&sentCount); err != nil {
+		t.Fatalf("count sent messages: %v", err)
+	}
+	if sentCount != 2 {
+		t.Fatalf("sent_messages rows = %d, want 2", sentCount)
+	}
+	assertNoStoredAttachmentPathInAPI(t, detail)
+}
+
+func buildTestMessage(t *testing.T, date time.Time) []byte {
+	t.Helper()
+	var body bytes.Buffer
+	writer := multipart.NewWriter(&body)
+	textPart, err := writer.CreatePart(textproto.MIMEHeader{
+		"Content-Type":              {"text/plain; charset=utf-8"},
+		"Content-Transfer-Encoding": {"quoted-printable"},
+	})
+	if err != nil {
+		t.Fatalf("create text part: %v", err)
+	}
+	_, _ = io.WriteString(textPart, "Hello Agent,\r\nThe report is attached.\r\n")
+	attachmentPart, err := writer.CreatePart(textproto.MIMEHeader{
+		"Content-Type":              {"text/plain; charset=utf-8"},
+		"Content-Disposition":       {`attachment; filename="../report.txt"`},
+		"Content-Transfer-Encoding": {"base64"},
+	})
+	if err != nil {
+		t.Fatalf("create attachment part: %v", err)
+	}
+	_, _ = io.WriteString(attachmentPart, "cmVwb3J0LWJvZHk=")
+	if err := writer.Close(); err != nil {
+		t.Fatalf("close multipart: %v", err)
+	}
+
+	headers := strings.Join([]string{
+		"Message-ID: <local-1@example.local>",
+		"From: Alice Example <alice@example.local>",
+		"To: Agent <agent@example.local>",
+		"Subject: Quarterly Report",
+		"Date: " + date.Format(time.RFC1123Z),
+		"Content-Type: multipart/mixed; boundary=" + writer.Boundary(),
+		"MIME-Version: 1.0",
+		"",
+		"",
+	}, "\r\n")
+	return []byte(headers + body.String())
+}
+
+type popMessage struct {
+	uid string
+	raw []byte
+}
+
+type fakePOP3Server struct {
+	host string
+	port int
+	ln   net.Listener
+}
+
+func newFakePOP3Server(t *testing.T, messages []popMessage) *fakePOP3Server {
+	t.Helper()
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("listen pop3: %v", err)
+	}
+	host, portString, _ := net.SplitHostPort(ln.Addr().String())
+	port, _ := strconv.Atoi(portString)
+	server := &fakePOP3Server{host: host, port: port, ln: ln}
+	t.Cleanup(func() { _ = ln.Close() })
+	go func() {
+		for {
+			conn, err := ln.Accept()
+			if err != nil {
+				return
+			}
+			go handlePOP3Conn(conn, messages)
+		}
+	}()
+	return server
+}
+
+func handlePOP3Conn(conn net.Conn, messages []popMessage) {
+	defer conn.Close()
+	_ = conn.SetDeadline(time.Now().Add(10 * time.Second))
+	reader := bufio.NewReader(conn)
+	writer := bufio.NewWriter(conn)
+	writeLine(writer, "+OK local POP3 ready")
+	for {
+		line, err := reader.ReadString('\n')
+		if err != nil {
+			return
+		}
+		line = strings.TrimRight(line, "\r\n")
+		parts := strings.Fields(line)
+		if len(parts) == 0 {
+			writeLine(writer, "-ERR empty command")
+			continue
+		}
+		switch strings.ToUpper(parts[0]) {
+		case "USER", "PASS", "NOOP":
+			writeLine(writer, "+OK")
+		case "UIDL":
+			if len(parts) > 1 {
+				idx, _ := strconv.Atoi(parts[1])
+				if idx <= 0 || idx > len(messages) {
+					writeLine(writer, "-ERR no such message")
+					continue
+				}
+				writeLine(writer, fmt.Sprintf("+OK %d %s", idx, messages[idx-1].uid))
+				continue
+			}
+			writeLine(writer, "+OK uid list follows")
+			for i, msg := range messages {
+				writeLine(writer, fmt.Sprintf("%d %s", i+1, msg.uid))
+			}
+			writeLine(writer, ".")
+		case "RETR":
+			if len(parts) < 2 {
+				writeLine(writer, "-ERR message id required")
+				continue
+			}
+			idx, _ := strconv.Atoi(parts[1])
+			if idx <= 0 || idx > len(messages) {
+				writeLine(writer, "-ERR no such message")
+				continue
+			}
+			writeLine(writer, fmt.Sprintf("+OK %d octets", len(messages[idx-1].raw)))
+			writeMultiline(writer, messages[idx-1].raw)
+		case "QUIT":
+			writeLine(writer, "+OK bye")
+			return
+		default:
+			writeLine(writer, "-ERR unsupported command")
+		}
+	}
+}
+
+func writeLine(w *bufio.Writer, line string) {
+	_, _ = w.WriteString(line + "\r\n")
+	_ = w.Flush()
+}
+
+func writeMultiline(w *bufio.Writer, raw []byte) {
+	for _, line := range strings.Split(strings.ReplaceAll(string(raw), "\r\n", "\n"), "\n") {
+		if strings.HasPrefix(line, ".") {
+			line = "." + line
+		}
+		_, _ = w.WriteString(line + "\r\n")
+	}
+	_, _ = w.WriteString(".\r\n")
+	_ = w.Flush()
+}
+
+type smtpMessage struct {
+	from       string
+	recipients []string
+	data       []byte
+}
+
+type fakeSMTPServer struct {
+	host string
+	port int
+	ln   net.Listener
+	mu   sync.Mutex
+	sent []smtpMessage
+}
+
+func newFakeSMTPServer(t *testing.T) *fakeSMTPServer {
+	t.Helper()
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("listen smtp: %v", err)
+	}
+	host, portString, _ := net.SplitHostPort(ln.Addr().String())
+	port, _ := strconv.Atoi(portString)
+	server := &fakeSMTPServer{host: host, port: port, ln: ln}
+	t.Cleanup(func() { _ = ln.Close() })
+	go func() {
+		for {
+			conn, err := ln.Accept()
+			if err != nil {
+				return
+			}
+			go server.handleConn(conn)
+		}
+	}()
+	return server
+}
+
+func (s *fakeSMTPServer) messages() []smtpMessage {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	out := make([]smtpMessage, len(s.sent))
+	copy(out, s.sent)
+	return out
+}
+
+func (s *fakeSMTPServer) handleConn(conn net.Conn) {
+	defer conn.Close()
+	_ = conn.SetDeadline(time.Now().Add(10 * time.Second))
+	reader := bufio.NewReader(conn)
+	writer := bufio.NewWriter(conn)
+	writeLine(writer, "220 local SMTP ready")
+	var current smtpMessage
+	for {
+		line, err := reader.ReadString('\n')
+		if err != nil {
+			return
+		}
+		line = strings.TrimRight(line, "\r\n")
+		upper := strings.ToUpper(line)
+		switch {
+		case strings.HasPrefix(upper, "EHLO ") || strings.HasPrefix(upper, "HELO "):
+			writeLine(writer, "250-localhost")
+			writeLine(writer, "250-AUTH PLAIN LOGIN")
+			writeLine(writer, "250 HELP")
+		case strings.HasPrefix(upper, "AUTH "):
+			writeLine(writer, "235 2.7.0 Authentication successful")
+		case strings.HasPrefix(upper, "MAIL FROM:"):
+			current = smtpMessage{from: extractSMTPPath(line)}
+			writeLine(writer, "250 OK")
+		case strings.HasPrefix(upper, "RCPT TO:"):
+			current.recipients = append(current.recipients, extractSMTPPath(line))
+			writeLine(writer, "250 OK")
+		case upper == "DATA":
+			writeLine(writer, "354 End data with <CR><LF>.<CR><LF>")
+			data, err := readSMTPData(reader)
+			if err != nil {
+				return
+			}
+			current.data = data
+			s.mu.Lock()
+			s.sent = append(s.sent, current)
+			s.mu.Unlock()
+			writeLine(writer, "250 OK queued")
+		case upper == "RSET":
+			current = smtpMessage{}
+			writeLine(writer, "250 OK")
+		case upper == "QUIT":
+			writeLine(writer, "221 bye")
+			return
+		default:
+			writeLine(writer, "250 OK")
+		}
+	}
+}
+
+func extractSMTPPath(line string) string {
+	_, value, ok := strings.Cut(line, ":")
+	if !ok {
+		return ""
+	}
+	value = strings.TrimSpace(value)
+	value = strings.TrimPrefix(value, "<")
+	value = strings.TrimSuffix(value, ">")
+	return value
+}
+
+func readSMTPData(reader *bufio.Reader) ([]byte, error) {
+	var out bytes.Buffer
+	for {
+		line, err := reader.ReadString('\n')
+		if err != nil {
+			return nil, err
+		}
+		if line == ".\r\n" || line == ".\n" {
+			return out.Bytes(), nil
+		}
+		if strings.HasPrefix(line, "..") {
+			line = line[1:]
+		}
+		out.WriteString(line)
+	}
+}
+
+func getJSON[T any](t *testing.T, url string) T {
+	t.Helper()
+	req, err := http.NewRequest(http.MethodGet, url, nil)
+	if err != nil {
+		t.Fatalf("new GET request: %v", err)
+	}
+	return doJSON[T](t, req, http.StatusOK)
+}
+
+func postJSON[T any](t *testing.T, url string, body any, status int) T {
+	t.Helper()
+	var reader io.Reader
+	if body != nil {
+		payload, err := json.Marshal(body)
+		if err != nil {
+			t.Fatalf("marshal body: %v", err)
+		}
+		reader = bytes.NewReader(payload)
+	}
+	req, err := http.NewRequest(http.MethodPost, url, reader)
+	if err != nil {
+		t.Fatalf("new POST request: %v", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+	return doJSON[T](t, req, status)
+}
+
+func doJSON[T any](t *testing.T, req *http.Request, status int) T {
+	t.Helper()
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		t.Fatalf("%s %s: %v", req.Method, req.URL, err)
+	}
+	defer resp.Body.Close()
+	payload, err := io.ReadAll(resp.Body)
+	if err != nil {
+		t.Fatalf("read response body: %v", err)
+	}
+	if resp.StatusCode != status {
+		t.Fatalf("%s %s status=%d want=%d body=%s", req.Method, req.URL, resp.StatusCode, status, payload)
+	}
+	var out T
+	if err := json.Unmarshal(payload, &out); err != nil {
+		t.Fatalf("decode response JSON: %v body=%s", err, payload)
+	}
+	return out
+}
+
+func containsAll(got, want []string) bool {
+	seen := map[string]bool{}
+	for _, item := range got {
+		seen[item] = true
+	}
+	for _, item := range want {
+		if !seen[item] {
+			return false
+		}
+	}
+	return true
+}
+
+func assertNoStoredAttachmentPathInAPI(t *testing.T, detail map[string]any) {
+	t.Helper()
+	encoded, err := json.Marshal(detail)
+	if err != nil {
+		t.Fatalf("marshal detail: %v", err)
+	}
+	if strings.Contains(string(encoded), string(os.PathSeparator)+"attachments"+string(os.PathSeparator)) {
+		t.Fatalf("API response appears to expose attachment storage path: %s", encoded)
+	}
+}
+
+func TestSentMessagesTableStoresFailedSendWithoutMarkingDraftSent(t *testing.T) {
+	ctx := context.Background()
+	dataDir := t.TempDir()
+	store, err := db.Open(filepath.Join(dataDir, "mail.db"))
+	if err != nil {
+		t.Fatalf("open db: %v", err)
+	}
+	t.Cleanup(func() { _ = store.Close() })
+	if err := store.Migrate(ctx); err != nil {
+		t.Fatalf("migrate db: %v", err)
+	}
+	cfg := &config.Config{AccountID: "local-fail"}
+	svc := service.NewWithOptions(store, nil, failingMailer{}, cfg.AccountID, service.Options{FromAddress: "agent@example.local"})
+	server := httptest.NewServer(api.New(cfg, store, svc).Handler())
+	t.Cleanup(server.Close)
+
+	draft := postJSON[map[string]any](t, server.URL+"/drafts", map[string]any{
+		"to":      []string{"recipient@example.local"},
+		"subject": "Will fail",
+		"body":    "Body",
+	}, http.StatusCreated)
+	postJSON[map[string]any](t, fmt.Sprintf("%s/drafts/%d/send", server.URL, int64(draft["id"].(float64))), nil, http.StatusBadGateway)
+
+	var status, lastError, sentStatus, errorMessage string
+	err = store.DB.QueryRowContext(ctx, `
+		SELECT d.status, COALESCE(d.last_error, ''), sm.status, COALESCE(sm.error_message, '')
+		FROM drafts d JOIN sent_messages sm ON sm.draft_id = d.id
+		WHERE d.id = ?`, int64(draft["id"].(float64))).Scan(&status, &lastError, &sentStatus, &errorMessage)
+	if err != nil {
+		t.Fatalf("query failed send rows: %v", err)
+	}
+	if status != "draft" || sentStatus != "failed" || lastError == "" || errorMessage == "" {
+		t.Fatalf("unexpected failed send persistence: draft=%q lastError=%q sent=%q error=%q", status, lastError, sentStatus, errorMessage)
+	}
+}
+
+type failingMailer struct{}
+
+func (failingMailer) Send(context.Context, mailsmtp.SendRequest) (mailsmtp.SendResult, error) {
+	return mailsmtp.SendResult{}, fmt.Errorf("local smtp failure")
+}
--- a/internal/model/model.go
+++ b/internal/model/model.go
@@ -0,0 +1,124 @@
+package model
+
+import "time"
+
+type Address struct {
+	Name  string `json:"name"`
+	Email string `json:"email"`
+}
+
+type ParsedAttachment struct {
+	Filename    string `json:"filename"`
+	ContentType string `json:"content_type"`
+	ContentID   string `json:"content_id,omitempty"`
+	SizeBytes   int64  `json:"size_bytes"`
+	Data        []byte `json:"-"`
+}
+
+type ParsedEmail struct {
+	MessageIDHeader string             `json:"message_id_header"`
+	InReplyTo       string             `json:"in_reply_to"`
+	References      string             `json:"references_header"`
+	Subject         string             `json:"subject"`
+	SenderName      string             `json:"sender_name"`
+	SenderEmail     string             `json:"sender_email"`
+	To              []Address          `json:"to"`
+	Cc              []Address          `json:"cc"`
+	DateHeader      string             `json:"date_header"`
+	SentAt          *time.Time         `json:"sent_at,omitempty"`
+	BodyText        string             `json:"body_text"`
+	BodyHTML        string             `json:"body_html"`
+	Attachments     []ParsedAttachment `json:"attachments"`
+}
+
+type Attachment struct {
+	ID          int64  `json:"attachment_id"`
+	MessageID   int64  `json:"-"`
+	Filename    string `json:"filename"`
+	ContentType string `json:"content_type"`
+	ContentID   string `json:"content_id,omitempty"`
+	SizeBytes   int64  `json:"size_bytes"`
+}
+
+type Label struct {
+	ID    int64  `json:"id"`
+	Name  string `json:"name"`
+	Color string `json:"color,omitempty"`
+}
+
+type LocalStatus struct {
+	Read      bool `json:"read"`
+	Processed bool `json:"processed"`
+	Archived  bool `json:"archived"`
+	Deleted   bool `json:"deleted"`
+	Replied   bool `json:"replied"`
+}
+
+type EmailSummary struct {
+	ID              int64       `json:"id"`
+	Subject         string      `json:"subject"`
+	SenderName      string      `json:"sender_name"`
+	SenderEmail     string      `json:"sender_email"`
+	To              []Address   `json:"to"`
+	Cc              []Address   `json:"cc,omitempty"`
+	DateHeader      string      `json:"date"`
+	SentAt          *time.Time  `json:"sent_at,omitempty"`
+	ReceivedAt      *time.Time  `json:"received_at,omitempty"`
+	Snippet         string      `json:"snippet"`
+	HasAttachment   bool        `json:"has_attachment"`
+	AttachmentCount int         `json:"attachment_count"`
+	LocalStatus     LocalStatus `json:"local_status"`
+	Labels          []Label     `json:"labels"`
+}
+
+type EmailDetail struct {
+	ID              int64        `json:"id"`
+	MessageIDHeader string       `json:"message_id_header"`
+	InReplyTo       string       `json:"in_reply_to,omitempty"`
+	References      string       `json:"references_header,omitempty"`
+	Subject         string       `json:"subject"`
+	SenderName      string       `json:"from_name"`
+	SenderEmail     string       `json:"from_email"`
+	To              []Address    `json:"to"`
+	Cc              []Address    `json:"cc"`
+	DateHeader      string       `json:"date"`
+	SentAt          *time.Time   `json:"sent_at,omitempty"`
+	ReceivedAt      *time.Time   `json:"received_at,omitempty"`
+	BodyText        string       `json:"body_text"`
+	BodyHTML        string       `json:"body_html"`
+	Attachments     []Attachment `json:"attachments"`
+	LocalStatus     LocalStatus  `json:"local_status"`
+	Labels          []Label      `json:"labels"`
+}
+
+type Draft struct {
+	ID             int64      `json:"id"`
+	To             []string   `json:"to"`
+	Cc             []string   `json:"cc"`
+	Bcc            []string   `json:"bcc"`
+	Subject        string     `json:"subject"`
+	Body           string     `json:"body"`
+	ReplyToEmailID *int64     `json:"reply_to_email_id,omitempty"`
+	Status         string     `json:"status"`
+	LastError      string     `json:"last_error,omitempty"`
+	SentMessageID  *int64     `json:"sent_message_id,omitempty"`
+	CreatedAt      *time.Time `json:"created_at,omitempty"`
+	UpdatedAt      *time.Time `json:"updated_at,omitempty"`
+}
+
+type FetchedMessage struct {
+	ServerID int    `json:"server_id"`
+	UID      string `json:"uid"`
+	Raw      []byte `json:"-"`
+	Error    string `json:"error,omitempty"`
+}
+
+type SentMessage struct {
+	ID              int64      `json:"id"`
+	DraftID         *int64     `json:"draft_id,omitempty"`
+	Subject         string     `json:"subject"`
+	MessageIDHeader string     `json:"message_id_header,omitempty"`
+	Status          string     `json:"status"`
+	ErrorMessage    string     `json:"error_message,omitempty"`
+	SentAt          *time.Time `json:"sent_at,omitempty"`
+}
--- a/internal/parser/parser.go
+++ b/internal/parser/parser.go
@@ -0,0 +1,228 @@
+package parser
+
+import (
+	"bytes"
+	"encoding/base64"
+	"fmt"
+	"io"
+	"mime"
+	"mime/multipart"
+	"mime/quotedprintable"
+	"net/mail"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"golang.org/x/net/html/charset"
+
+	"internal-mail-skill/internal/model"
+)
+
+func Parse(raw []byte) (model.ParsedEmail, error) {
+	msg, err := mail.ReadMessage(bytes.NewReader(raw))
+	if err != nil {
+		return model.ParsedEmail{}, fmt.Errorf("read message: %w", err)
+	}
+
+	parsed := model.ParsedEmail{
+		MessageIDHeader: strings.TrimSpace(msg.Header.Get("Message-ID")),
+		InReplyTo:       strings.TrimSpace(msg.Header.Get("In-Reply-To")),
+		References:      strings.TrimSpace(msg.Header.Get("References")),
+		Subject:         decodeHeader(msg.Header.Get("Subject")),
+		DateHeader:      strings.TrimSpace(msg.Header.Get("Date")),
+	}
+	if sentAt, err := mail.ParseDate(parsed.DateHeader); err == nil {
+		parsed.SentAt = &sentAt
+	}
+	if from, err := mail.ParseAddress(msg.Header.Get("From")); err == nil {
+		parsed.SenderName = decodeHeader(from.Name)
+		parsed.SenderEmail = strings.ToLower(from.Address)
+	}
+	parsed.To = parseAddressList(msg.Header.Get("To"))
+	parsed.Cc = parseAddressList(msg.Header.Get("Cc"))
+
+	if err := parsePart(mail.Header(msg.Header), msg.Body, &parsed); err != nil {
+		return model.ParsedEmail{}, err
+	}
+	return parsed, nil
+}
+
+func parsePart(header mail.Header, body io.Reader, out *model.ParsedEmail) error {
+	mediaType, params, err := mime.ParseMediaType(header.Get("Content-Type"))
+	if err != nil || mediaType == "" {
+		mediaType = "text/plain"
+	}
+	mediaType = strings.ToLower(mediaType)
+
+	if strings.HasPrefix(mediaType, "multipart/") {
+		boundary := params["boundary"]
+		if boundary == "" {
+			return fmt.Errorf("multipart message missing boundary")
+		}
+		mr := multipart.NewReader(body, boundary)
+		for {
+			part, err := mr.NextPart()
+			if err == io.EOF {
+				return nil
+			}
+			if err != nil {
+				return fmt.Errorf("read multipart: %w", err)
+			}
+			if err := parsePart(mail.Header(part.Header), part, out); err != nil {
+				return err
+			}
+		}
+	}
+
+	decoded := transferDecodedReader(header, body)
+	filename := partFilename(header)
+	disposition := strings.ToLower(header.Get("Content-Disposition"))
+	isAttachment := filename != "" || strings.Contains(disposition, "attachment")
+
+	if !isAttachment && strings.HasPrefix(mediaType, "text/") {
+		text, err := readText(decoded, params["charset"])
+		if err != nil {
+			return fmt.Errorf("read text part: %w", err)
+		}
+		switch mediaType {
+		case "text/html":
+			appendText(&out.BodyHTML, text)
+		default:
+			appendText(&out.BodyText, text)
+		}
+		return nil
+	}
+
+	data, err := io.ReadAll(decoded)
+	if err != nil {
+		return fmt.Errorf("read attachment: %w", err)
+	}
+	if filename == "" {
+		filename = "attachment.bin"
+	}
+	out.Attachments = append(out.Attachments, model.ParsedAttachment{
+		Filename:    sanitizeFilename(filename),
+		ContentType: mediaType,
+		ContentID:   trimAngle(header.Get("Content-ID")),
+		SizeBytes:   int64(len(data)),
+		Data:        data,
+	})
+	return nil
+}
+
+func decodeHeader(value string) string {
+	value = strings.TrimSpace(value)
+	if value == "" {
+		return ""
+	}
+	decoder := &mime.WordDecoder{CharsetReader: charset.NewReaderLabel}
+	decoded, err := decoder.DecodeHeader(value)
+	if err != nil {
+		return value
+	}
+	return decoded
+}
+
+func parseAddressList(value string) []model.Address {
+	value = strings.TrimSpace(value)
+	if value == "" {
+		return nil
+	}
+	list, err := mail.ParseAddressList(value)
+	if err != nil {
+		decoded := decodeHeader(value)
+		list, err = mail.ParseAddressList(decoded)
+		if err != nil {
+			return nil
+		}
+	}
+	out := make([]model.Address, 0, len(list))
+	for _, addr := range list {
+		out = append(out, model.Address{
+			Name:  decodeHeader(addr.Name),
+			Email: strings.ToLower(addr.Address),
+		})
+	}
+	return out
+}
+
+func transferDecodedReader(header mail.Header, r io.Reader) io.Reader {
+	switch strings.ToLower(strings.TrimSpace(header.Get("Content-Transfer-Encoding"))) {
+	case "base64":
+		return base64.NewDecoder(base64.StdEncoding, r)
+	case "quoted-printable":
+		return quotedprintable.NewReader(r)
+	default:
+		return r
+	}
+}
+
+func readText(r io.Reader, label string) (string, error) {
+	if label != "" {
+		cr, err := charset.NewReaderLabel(label, r)
+		if err == nil {
+			r = cr
+		}
+	}
+	data, err := io.ReadAll(r)
+	if err != nil {
+		return "", err
+	}
+	return string(data), nil
+}
+
+func partFilename(header mail.Header) string {
+	if disp := header.Get("Content-Disposition"); disp != "" {
+		_, params, err := mime.ParseMediaType(disp)
+		if err == nil && params["filename"] != "" {
+			return decodeHeader(params["filename"])
+		}
+	}
+	if ct := header.Get("Content-Type"); ct != "" {
+		_, params, err := mime.ParseMediaType(ct)
+		if err == nil && params["name"] != "" {
+			return decodeHeader(params["name"])
+		}
+	}
+	return ""
+}
+
+func appendText(dst *string, value string) {
+	if strings.TrimSpace(value) == "" {
+		return
+	}
+	if strings.TrimSpace(*dst) == "" {
+		*dst = value
+		return
+	}
+	*dst += "\n" + value
+}
+
+func sanitizeFilename(name string) string {
+	name = filepath.Base(strings.TrimSpace(name))
+	name = strings.ReplaceAll(name, "\x00", "")
+	name = strings.ReplaceAll(name, "/", "_")
+	name = strings.ReplaceAll(name, "\\", "_")
+	if name == "." || name == "" {
+		return "attachment.bin"
+	}
+	return name
+}
+
+func trimAngle(value string) string {
+	value = strings.TrimSpace(value)
+	value = strings.TrimPrefix(value, "<")
+	value = strings.TrimSuffix(value, ">")
+	return value
+}
+
+func ParseTimeRFC3339(value string) *time.Time {
+	if value == "" {
+		return nil
+	}
+	t, err := time.Parse(time.RFC3339Nano, value)
+	if err != nil {
+		return nil
+	}
+	return &t
+}
--- a/internal/parser/parser_test.go
+++ b/internal/parser/parser_test.go
@@ -0,0 +1,63 @@
+package parser
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestParseMultipartEmailWithAttachment(t *testing.T) {
+	raw := strings.Join([]string{
+		"Message-ID: <m1@example.com>",
+		"Subject: =?UTF-8?B?5rWL6K+V6YKu5Lu2?=",
+		"From: =?UTF-8?B?5byg5LiJ?= <sender@example.com>",
+		"To: receiver@example.com",
+		"Cc: cc@example.com",
+		"Date: Tue, 04 Jun 2024 12:00:00 +0800",
+		"MIME-Version: 1.0",
+		"Content-Type: multipart/mixed; boundary=mix",
+		"",
+		"--mix",
+		"Content-Type: multipart/alternative; boundary=alt",
+		"",
+		"--alt",
+		"Content-Type: text/plain; charset=utf-8",
+		"",
+		"plain body",
+		"--alt",
+		"Content-Type: text/html; charset=utf-8",
+		"",
+		"<p>html body</p>",
+		"--alt--",
+		"--mix",
+		"Content-Type: text/plain; name=\"note.txt\"",
+		"Content-Disposition: attachment; filename=\"note.txt\"",
+		"Content-Transfer-Encoding: base64",
+		"",
+		"YXR0YWNobWVudA==",
+		"--mix--",
+		"",
+	}, "\r\n")
+
+	msg, err := Parse([]byte(raw))
+	if err != nil {
+		t.Fatalf("Parse() error = %v", err)
+	}
+	if msg.Subject != "测试邮件" {
+		t.Fatalf("Subject = %q", msg.Subject)
+	}
+	if msg.SenderName != "张三" || msg.SenderEmail != "sender@example.com" {
+		t.Fatalf("sender = %q <%s>", msg.SenderName, msg.SenderEmail)
+	}
+	if strings.TrimSpace(msg.BodyText) != "plain body" {
+		t.Fatalf("BodyText = %q", msg.BodyText)
+	}
+	if !strings.Contains(msg.BodyHTML, "html body") {
+		t.Fatalf("BodyHTML = %q", msg.BodyHTML)
+	}
+	if len(msg.Attachments) != 1 {
+		t.Fatalf("attachments = %d", len(msg.Attachments))
+	}
+	if msg.Attachments[0].Filename != "note.txt" || string(msg.Attachments[0].Data) != "attachment" {
+		t.Fatalf("attachment = %#v", msg.Attachments[0])
+	}
+}
--- a/internal/pop3/pop3.go
+++ b/internal/pop3/pop3.go
@@ -0,0 +1,69 @@
+package pop3
+
+import (
+	"context"
+	"fmt"
+
+	gopop3 "github.com/knadh/go-pop3"
+
+	"internal-mail-skill/internal/config"
+	"internal-mail-skill/internal/model"
+)
+
+type Fetcher struct {
+	cfg config.POP3Config
+}
+
+func NewFetcher(cfg config.POP3Config) *Fetcher {
+	return &Fetcher{cfg: cfg}
+}
+
+func (f *Fetcher) Fetch(ctx context.Context) ([]model.FetchedMessage, error) {
+	if f.cfg.Host == "" {
+		return nil, fmt.Errorf("POP3_HOST is required")
+	}
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	default:
+	}
+
+	client := gopop3.New(gopop3.Opt{
+		Host:        f.cfg.Host,
+		Port:        f.cfg.Port,
+		TLSEnabled:  f.cfg.UseTLS,
+		DialTimeout: f.cfg.Timeout(),
+	})
+	conn, err := client.NewConn()
+	if err != nil {
+		return nil, fmt.Errorf("connect POP3: %w", err)
+	}
+	defer conn.Quit()
+
+	if err := conn.Auth(f.cfg.Username, f.cfg.Password); err != nil {
+		return nil, fmt.Errorf("POP3 auth: %w", err)
+	}
+	ids, err := conn.Uidl(0)
+	if err != nil {
+		return nil, fmt.Errorf("POP3 UIDL: %w", err)
+	}
+	out := make([]model.FetchedMessage, 0, len(ids))
+	for _, item := range ids {
+		select {
+		case <-ctx.Done():
+			return out, ctx.Err()
+		default:
+		}
+		raw, err := conn.RetrRaw(item.ID)
+		if err != nil {
+			out = append(out, model.FetchedMessage{ServerID: item.ID, UID: item.UID, Error: fmt.Sprintf("POP3 RETR %d: %v", item.ID, err)})
+			continue
+		}
+		out = append(out, model.FetchedMessage{
+			ServerID: item.ID,
+			UID:      item.UID,
+			Raw:      raw.Bytes(),
+		})
+	}
+	return out, nil
+}
--- a/internal/service/service.go
+++ b/internal/service/service.go
--- a/internal/service/service_test.go
+++ b/internal/service/service_test.go
@@ -0,0 +1,210 @@
+package service
+
+import (
+	"context"
+	"errors"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"internal-mail-skill/internal/db"
+	"internal-mail-skill/internal/model"
+	mailsmtp "internal-mail-skill/internal/smtp"
+)
+
+func TestThreadAssemblyLinksReferences(t *testing.T) {
+	ctx := context.Background()
+	store, err := db.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer store.Close()
+	if err := store.Migrate(ctx); err != nil {
+		t.Fatal(err)
+	}
+	svc := New(store, nil, nil, "default")
+
+	root, err := svc.SaveParsedEmail(ctx, SaveEmailInput{
+		POP3UID: "uid-root",
+		Parsed: model.ParsedEmail{
+			MessageIDHeader: "<root@example.com>",
+			Subject:         "Root",
+			SenderEmail:     "a@example.com",
+		},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	reply, err := svc.SaveParsedEmail(ctx, SaveEmailInput{
+		POP3UID: "uid-reply",
+		Parsed: model.ParsedEmail{
+			MessageIDHeader: "<reply@example.com>",
+			InReplyTo:       "<root@example.com>",
+			References:      "<root@example.com>",
+			Subject:         "Re: Root",
+			SenderEmail:     "b@example.com",
+		},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	thread, err := svc.GetThread(ctx, reply)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(thread) != 2 || thread[0].ID != root || thread[1].ID != reply {
+		t.Fatalf("thread = %#v", thread)
+	}
+}
+
+func TestSearchMarkLabelsAndDraftLifecycle(t *testing.T) {
+	ctx := context.Background()
+	store, err := db.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer store.Close()
+	if err := store.Migrate(ctx); err != nil {
+		t.Fatal(err)
+	}
+	svc := New(store, nil, nil, "default")
+
+	emailID, err := svc.SaveParsedEmail(ctx, SaveEmailInput{
+		POP3UID: "uid-1",
+		Parsed: model.ParsedEmail{
+			MessageIDHeader: "<m@example.com>",
+			Subject:         "Quarterly Plan",
+			BodyText:        "Please review",
+			SenderEmail:     "boss@example.com",
+		},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := svc.MarkEmail(ctx, emailID, MarkInput{Read: boolPtr(true), Processed: boolPtr(true)}); err != nil {
+		t.Fatal(err)
+	}
+	label, err := svc.CreateLabel(ctx, "work", "#336699")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := svc.ApplyLabels(ctx, []int64{emailID}, []int64{label.ID}, "add"); err != nil {
+		t.Fatal(err)
+	}
+	results, err := svc.SearchEmails(ctx, SearchFilters{Q: "Quarterly", Read: boolPtr(true), Limit: 10})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(results) != 1 || results[0].Labels[0].Name != "work" {
+		t.Fatalf("search results = %#v", results)
+	}
+
+	draft, err := svc.CreateDraft(ctx, DraftInput{To: []string{"x@example.com"}, Subject: "Draft", Body: "Hi"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	updated, err := svc.UpdateDraft(ctx, draft.ID, DraftInput{To: []string{"x@example.com"}, Subject: "Updated", Body: "Hello"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if updated.Subject != "Updated" {
+		t.Fatalf("updated subject = %q", updated.Subject)
+	}
+}
+
+func TestSaveParsedEmailRollsBackWhenAttachmentStorageFails(t *testing.T) {
+	ctx := context.Background()
+	store, err := db.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer store.Close()
+	if err := store.Migrate(ctx); err != nil {
+		t.Fatal(err)
+	}
+	dir := t.TempDir()
+	blocker := filepath.Join(dir, "attachments-blocker")
+	if err := os.WriteFile(blocker, []byte("not a directory"), 0600); err != nil {
+		t.Fatal(err)
+	}
+	svc := NewWithOptions(store, nil, nil, "default", Options{AttachmentDir: blocker})
+
+	_, err = svc.SaveParsedEmail(ctx, SaveEmailInput{
+		POP3UID: "uid-broken-attachment",
+		Parsed: model.ParsedEmail{
+			MessageIDHeader: "<broken@example.com>",
+			Subject:         "Broken Attachment",
+			SenderEmail:     "a@example.com",
+			Attachments: []model.ParsedAttachment{{
+				Filename:    "note.txt",
+				ContentType: "text/plain",
+				SizeBytes:   4,
+				Data:        []byte("nope"),
+			}},
+		},
+	})
+	if err == nil {
+		t.Fatal("SaveParsedEmail() error = nil, want attachment storage failure")
+	}
+
+	results, err := svc.SearchEmails(ctx, SearchFilters{Q: "Broken Attachment", Limit: 10})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(results) != 0 {
+		t.Fatalf("failed save left searchable message: %#v", results)
+	}
+}
+
+func TestSendDraftIsIdempotentAfterSuccess(t *testing.T) {
+	ctx := context.Background()
+	store, err := db.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer store.Close()
+	if err := store.Migrate(ctx); err != nil {
+		t.Fatal(err)
+	}
+	mailer := &fakeMailer{}
+	svc := NewWithOptions(store, nil, mailer, "default", Options{FromAddress: "sender@example.com"})
+
+	draft, err := svc.CreateDraft(ctx, DraftInput{To: []string{"x@example.com"}, Subject: "Once", Body: "hello"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	first, err := svc.SendDraft(ctx, draft.ID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	second, err := svc.SendDraft(ctx, draft.ID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if mailer.calls != 1 {
+		t.Fatalf("mailer calls = %d, want 1", mailer.calls)
+	}
+	if second.SentMessage.ID != first.SentMessage.ID {
+		t.Fatalf("second send message id = %d, want %d", second.SentMessage.ID, first.SentMessage.ID)
+	}
+}
+
+func boolPtr(v bool) *bool { return &v }
+
+type fakeMailer struct {
+	calls int
+	err   error
+}
+
+func (f *fakeMailer) Send(ctx context.Context, req mailsmtp.SendRequest) (mailsmtp.SendResult, error) {
+	f.calls++
+	if f.err != nil {
+		return mailsmtp.SendResult{}, f.err
+	}
+	if req.FromAddress == "" {
+		return mailsmtp.SendResult{}, errors.New("from required")
+	}
+	return mailsmtp.SendResult{MessageIDHeader: "<sent@example.com>", SentAt: time.Now().UTC()}, nil
+}
--- a/internal/smtp/message_test.go
+++ b/internal/smtp/message_test.go
@@ -0,0 +1,90 @@
+package smtp
+
+import (
+	stdsmtp "net/smtp"
+	"strings"
+	"testing"
+
+	"internal-mail-skill/internal/config"
+)
+
+func TestBuildMessageOmitsBccHeaderButKeepsRecipients(t *testing.T) {
+	req := SendRequest{
+		FromAddress: "agent@example.com",
+		FromName:    "Agent",
+		To:          []string{"to@example.com"},
+		Cc:          []string{"cc@example.com"},
+		Bcc:         []string{"hidden@example.com"},
+		Subject:     "Hello",
+		Body:        "Body",
+	}
+
+	msg, recipients, err := BuildMessage(req)
+	if err != nil {
+		t.Fatalf("BuildMessage() error = %v", err)
+	}
+	raw := string(msg)
+	if strings.Contains(raw, "Bcc:") || strings.Contains(raw, "hidden@example.com") {
+		t.Fatalf("raw message leaked Bcc: %s", raw)
+	}
+	if len(recipients) != 3 {
+		t.Fatalf("recipients = %#v", recipients)
+	}
+	if recipients[2] != "hidden@example.com" {
+		t.Fatalf("Bcc missing from envelope recipients: %#v", recipients)
+	}
+}
+
+func TestAuthForConfigRequiresExplicitOptInForCleartextAuth(t *testing.T) {
+	cfg := config.SMTPConfig{
+		Host:         "smtp.example.local",
+		Username:     "user",
+		Password:     "secret",
+		AuthRequired: true,
+	}
+
+	if _, err := authForConfig(cfg); err == nil {
+		t.Fatal("authForConfig() error = nil, want cleartext auth rejection")
+	}
+
+	cfg.AllowInsecureAuth = true
+	auth, err := authForConfig(cfg)
+	if err != nil {
+		t.Fatalf("authForConfig() with opt-in error = %v", err)
+	}
+	proto, _, err := auth.Start(&stdsmtp.ServerInfo{Name: cfg.Host, TLS: false})
+	if err != nil {
+		t.Fatalf("insecure auth Start() error = %v", err)
+	}
+	if proto != "PLAIN" {
+		t.Fatalf("proto = %q, want PLAIN", proto)
+	}
+
+	cfg.AllowInsecureAuth = false
+	cfg.UseSTARTTLS = true
+	auth, err = authForConfig(cfg)
+	if err != nil {
+		t.Fatalf("authForConfig() over STARTTLS error = %v", err)
+	}
+	if _, _, err := auth.Start(&stdsmtp.ServerInfo{Name: cfg.Host, TLS: true}); err != nil {
+		t.Fatalf("TLS auth Start() error = %v", err)
+	}
+}
+
+func TestAuthForConfigAllowsImplicitTLSAuth(t *testing.T) {
+	cfg := config.SMTPConfig{
+		Host:         "smtp.example.local",
+		Username:     "user",
+		Password:     "secret",
+		AuthRequired: true,
+		UseTLS:       true,
+	}
+
+	auth, err := authForConfig(cfg)
+	if err != nil {
+		t.Fatalf("authForConfig() error = %v", err)
+	}
+	if _, _, err := auth.Start(&stdsmtp.ServerInfo{Name: cfg.Host, TLS: false}); err != nil {
+		t.Fatalf("implicit TLS auth Start() error = %v", err)
+	}
+}
--- a/internal/smtp/smtp.go
+++ b/internal/smtp/smtp.go
@@ -0,0 +1,252 @@
+package smtp
+
+import (
+	"bytes"
+	"context"
+	"crypto/rand"
+	"crypto/tls"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"mime"
+	"net"
+	"net/mail"
+	stdsmtp "net/smtp"
+	"os"
+	"strings"
+	"time"
+
+	"internal-mail-skill/internal/config"
+)
+
+type SendRequest struct {
+	FromAddress     string
+	FromName        string
+	To              []string
+	Cc              []string
+	Bcc             []string
+	Subject         string
+	Body            string
+	InReplyTo       string
+	References      string
+	MessageIDHeader string
+}
+
+type SendResult struct {
+	MessageIDHeader string
+	Raw             []byte
+	Recipients      []string
+	SentAt          time.Time
+}
+
+type Sender struct {
+	cfg config.SMTPConfig
+}
+
+func NewSender(cfg config.SMTPConfig) *Sender {
+	return &Sender{cfg: cfg}
+}
+
+func (s *Sender) Send(ctx context.Context, req SendRequest) (SendResult, error) {
+	if req.FromAddress == "" {
+		req.FromAddress = s.cfg.FromAddress
+	}
+	if req.FromName == "" {
+		req.FromName = s.cfg.FromName
+	}
+	raw, recipients, err := BuildMessage(req)
+	if err != nil {
+		return SendResult{}, err
+	}
+	if len(recipients) == 0 {
+		return SendResult{}, fmt.Errorf("no recipients")
+	}
+	if s.cfg.Host == "" {
+		return SendResult{}, fmt.Errorf("SMTP_HOST is required")
+	}
+	auth, err := authForConfig(s.cfg)
+	if err != nil {
+		return SendResult{}, err
+	}
+	if err := s.sendRaw(ctx, req.FromAddress, recipients, raw, auth); err != nil {
+		return SendResult{}, err
+	}
+	return SendResult{
+		MessageIDHeader: extractHeader(raw, "Message-ID"),
+		Raw:             raw,
+		Recipients:      recipients,
+		SentAt:          time.Now().UTC(),
+	}, nil
+}
+
+func BuildMessage(req SendRequest) ([]byte, []string, error) {
+	if req.FromAddress == "" {
+		return nil, nil, fmt.Errorf("from address is required")
+	}
+	recipients := append([]string{}, req.To...)
+	recipients = append(recipients, req.Cc...)
+	recipients = append(recipients, req.Bcc...)
+	if len(recipients) == 0 {
+		return nil, nil, fmt.Errorf("at least one recipient is required")
+	}
+	messageID := req.MessageIDHeader
+	if messageID == "" {
+		messageID = newMessageID()
+	}
+	var b bytes.Buffer
+	writeHeader(&b, "From", (&mail.Address{Name: req.FromName, Address: req.FromAddress}).String())
+	writeHeader(&b, "To", strings.Join(req.To, ", "))
+	if len(req.Cc) > 0 {
+		writeHeader(&b, "Cc", strings.Join(req.Cc, ", "))
+	}
+	writeHeader(&b, "Subject", mime.QEncoding.Encode("utf-8", req.Subject))
+	writeHeader(&b, "Date", time.Now().Format(time.RFC1123Z))
+	writeHeader(&b, "Message-ID", messageID)
+	if req.InReplyTo != "" {
+		writeHeader(&b, "In-Reply-To", req.InReplyTo)
+	}
+	if req.References != "" {
+		writeHeader(&b, "References", req.References)
+	}
+	writeHeader(&b, "MIME-Version", "1.0")
+	writeHeader(&b, "Content-Type", `text/plain; charset="utf-8"`)
+	writeHeader(&b, "Content-Transfer-Encoding", "8bit")
+	b.WriteString("\r\n")
+	body := strings.ReplaceAll(req.Body, "\n", "\r\n")
+	body = strings.ReplaceAll(body, "\r\r\n", "\r\n")
+	b.WriteString(body)
+	if !strings.HasSuffix(body, "\r\n") {
+		b.WriteString("\r\n")
+	}
+	return b.Bytes(), recipients, nil
+}
+
+func (s *Sender) sendRaw(ctx context.Context, from string, recipients []string, raw []byte, auth stdsmtp.Auth) error {
+	timeout := s.cfg.Timeout()
+	if timeout <= 0 {
+		timeout = 30 * time.Second
+	}
+	address := net.JoinHostPort(s.cfg.Host, fmt.Sprintf("%d", s.cfg.Port))
+	dialer := &net.Dialer{Timeout: timeout}
+	var conn net.Conn
+	var err error
+	if s.cfg.UseTLS {
+		conn, err = tls.DialWithDialer(dialer, "tcp", address, &tls.Config{ServerName: s.cfg.Host, MinVersion: tls.VersionTLS12})
+	} else {
+		conn, err = dialer.DialContext(ctx, "tcp", address)
+	}
+	if err != nil {
+		return fmt.Errorf("connect SMTP: %w", err)
+	}
+	defer conn.Close()
+
+	client, err := stdsmtp.NewClient(conn, s.cfg.Host)
+	if err != nil {
+		return fmt.Errorf("create SMTP client: %w", err)
+	}
+	defer client.Close()
+
+	if s.cfg.UseSTARTTLS {
+		if err := client.StartTLS(&tls.Config{ServerName: s.cfg.Host, MinVersion: tls.VersionTLS12}); err != nil {
+			return fmt.Errorf("starttls: %w", err)
+		}
+	}
+	if auth != nil {
+		if err := client.Auth(auth); err != nil {
+			return fmt.Errorf("smtp auth: %w", err)
+		}
+	}
+	if err := client.Mail(from); err != nil {
+		return fmt.Errorf("smtp MAIL FROM: %w", err)
+	}
+	for _, recipient := range recipients {
+		if strings.TrimSpace(recipient) == "" {
+			continue
+		}
+		if err := client.Rcpt(recipient); err != nil {
+			return fmt.Errorf("smtp RCPT TO %s: %w", recipient, err)
+		}
+	}
+	writer, err := client.Data()
+	if err != nil {
+		return fmt.Errorf("smtp DATA: %w", err)
+	}
+	if _, err := io.Copy(writer, bytes.NewReader(raw)); err != nil {
+		_ = writer.Close()
+		return fmt.Errorf("write SMTP body: %w", err)
+	}
+	if err := writer.Close(); err != nil {
+		return fmt.Errorf("close SMTP body: %w", err)
+	}
+	if err := client.Quit(); err != nil {
+		return fmt.Errorf("smtp quit: %w", err)
+	}
+	return nil
+}
+
+func authForConfig(cfg config.SMTPConfig) (stdsmtp.Auth, error) {
+	if !cfg.AuthRequired {
+		return nil, nil
+	}
+	if !cfg.UseTLS && !cfg.UseSTARTTLS {
+		if cfg.AllowInsecureAuth {
+			return plainAuthNoTLSCheck{username: cfg.Username, password: cfg.Password}, nil
+		}
+		if cfg.Host != "localhost" && cfg.Host != "127.0.0.1" && cfg.Host != "::1" {
+			return nil, fmt.Errorf("SMTP auth over cleartext requires SMTP_USE_TLS=true, SMTP_USE_STARTTLS=true, or SMTP_ALLOW_INSECURE_AUTH=true")
+		}
+	}
+	if cfg.UseTLS {
+		return plainAuthNoTLSCheck{username: cfg.Username, password: cfg.Password}, nil
+	}
+	return stdsmtp.PlainAuth("", cfg.Username, cfg.Password, cfg.Host), nil
+}
+
+type plainAuthNoTLSCheck struct {
+	username string
+	password string
+}
+
+func (a plainAuthNoTLSCheck) Start(server *stdsmtp.ServerInfo) (string, []byte, error) {
+	resp := []byte("\x00" + a.username + "\x00" + a.password)
+	return "PLAIN", resp, nil
+}
+
+func (a plainAuthNoTLSCheck) Next(fromServer []byte, more bool) ([]byte, error) {
+	if more {
+		return nil, fmt.Errorf("unexpected server challenge for PLAIN auth")
+	}
+	return nil, nil
+}
+
+func writeHeader(b *bytes.Buffer, key, value string) {
+	if strings.TrimSpace(value) == "" {
+		return
+	}
+	b.WriteString(key)
+	b.WriteString(": ")
+	b.WriteString(value)
+	b.WriteString("\r\n")
+}
+
+func newMessageID() string {
+	host, err := os.Hostname()
+	if err != nil || host == "" {
+		host = "localhost"
+	}
+	var random [8]byte
+	if _, err := rand.Read(random[:]); err != nil {
+		return fmt.Sprintf("<%d@%s>", time.Now().UnixNano(), host)
+	}
+	return fmt.Sprintf("<%d.%s@%s>", time.Now().UnixNano(), hex.EncodeToString(random[:]), host)
+}
+
+func extractHeader(raw []byte, name string) string {
+	prefix := strings.ToLower(name) + ":"
+	for _, line := range strings.Split(string(raw), "\r\n") {
+		if strings.HasPrefix(strings.ToLower(line), prefix) {
+			return strings.TrimSpace(line[len(name)+1:])
+		}
+	}
+	return ""
+}