lyrathorpe
a29889b731
Fix several POP3/IMAP proxy correctness defects: - RETR returned an empty body because fetch_message kept only top-level bytes from the imaplib FETCH response; extract the RFC822 literal from the response tuple instead. - DELE marks were wiped mid-session because STAT/LIST/UIDL refreshed the mailbox and cleared the deleted set. Snapshot the UID list once at authentication and keep the maildrop static for the session lifetime. - RETR/TOP output now normalises line endings to CRLF, byte-stuffs lines beginning with ".", and emits the terminating ".\r\n" per RFC 1939. - STAT/LIST batch message sizes via a single threaded UID FETCH and the IMAP client now uses a 30s socket timeout, keeping blocking work off the event loop. - Implement the POP3 TOP command (headers plus first n body lines). Fixes #1 Fixes #2 Fixes #3 Fixes #5 Fixes #6 Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Legacy Email Proxy
Proxy an unauthenticated, unencrypted POP3 / SMTP server to authenticated IMAPS and SMTPS backends.
Features
- Exposes legacy
POP3on0.0.0.0:110and legacySMTPon0.0.0.0:25 - Forwards POP3 mailbox access to an IMAP backend
- Forwards SMTP submissions to an SMTPS backend
- Backend host, ports, and credentials are configured via environment variables
Environment Variables
-
POP3_BIND_ADDR(default0.0.0.0) -
POP3_BIND_PORT(default110) -
SMTP_BIND_ADDR(default0.0.0.0) -
SMTP_BIND_PORT(default25) -
BACKEND_IMAP_HOST -
BACKEND_IMAP_PORT(default993) -
BACKEND_IMAP_USER -
BACKEND_IMAP_PASS -
BACKEND_IMAP_USE_SSL(defaulttrue) -
BACKEND_IMAP_USE_STARTTLS(defaultfalse) -
BACKEND_SMTP_HOST -
BACKEND_SMTP_PORT(default465) -
BACKEND_SMTP_USER -
BACKEND_SMTP_PASS -
BACKEND_SMTP_USE_SSL(defaulttrue) -
BACKEND_SMTP_USE_TLS(defaultfalse)
Build and run
This project targets the latest Python LTS release. The included Dockerfile uses python:3.12-slim, which is compatible with Python 3.12 and later LTS releases.
docker build -t legacy-email-proxy .
docker run --rm -p 110:110 -p 25:25 \
-e BACKEND_IMAP_HOST=imap.example.com \
-e BACKEND_IMAP_PORT=993 \
-e BACKEND_IMAP_USER=imap-user \
-e BACKEND_IMAP_PASS=imap-pass \
-e BACKEND_SMTP_HOST=smtp.example.com \
-e BACKEND_SMTP_PORT=465 \
-e BACKEND_SMTP_USER=smtp-user \
-e BACKEND_SMTP_PASS=smtp-pass \
legacy-email-proxy
Tests
Install development dependencies and run the test suite:
python -m venv .venv
source .venv/bin/activate
python -m pip install --upgrade pip
pip install -r requirements-dev.txt
pytest -q
Notes
This implementation begins the proxy with a minimal POP3 command set and SMTP delivery path. It is designed to start development on the required application architecture.