Implement internal mail skill MVP

.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