wMailServer

A very simple mail system developed using Python. It only supports core SMTP and POP3 features and is built for easy deployment and local testing. The server stores mail on disk (no database required), supports TLS, basic authentication, and simple relay capabilities.

Key features

• SMTP with EHLO/STARTTLS and authentication (LOGIN and PLAIN over TLS).
• POP3 with AUTH, TOP, UIDL, LAST, and optional implicit TLS (port 995) or explicit STLS.
• File-based mail storage per user (no DB).
• Mail relay support to send outgoing mail through an upstream relay when direct delivery is unavailable.
• Simple DSN/notifications for delivery status and failures.
• Lightweight per-group user management (usermanager/<group>/group.json).

Quick start

1. Install Python 3.8+ on your host.
2. Edit config/config.json to configure SMTP/POP3 services, ports and UserGroups certificate paths.
3. Make sure any certificate files referenced in UserGroups exist and are readable by the process when TLS is enabled.
4. Start the server:

python3 wMailServer.py

5. On first run the server creates required directories; stop it, review and update any generated configs, then restart.

Configuration

• config/config.json contains service port definitions, SSL flags and user-group mappings.
• usermanager/<group>/group.json stores users and domain bindings for each group.
• sample/config includes example config and template files to copy and adapt.

Security notes

• Always require TLS for AUTH PLAIN (credentials must not be sent in cleartext).
• If you enable implicit SSL ports (e.g. 465 or 995), ensure certificate paths are correct and the server process can access them; otherwise TLS negotiation will fail.

Compatibility

• POP3 CAPA advertises extensions such as UTF8. Some clients may send UTF8 as a command — wMailServer accepts UTF8 as a no-op for compatibility with such clients (for example Outlook).

Development & extension

• Command handlers live in SMTPService.py and POP3Service.py and are straightforward to extend.
• An IMAPService.py placeholder exists as a starting point for future IMAP support.