Mail accounts and mail clients
This page is the HTML version of the all2all mail setup manuals. The older PDF manuals remain available for download while the web documentation is being rewritten.
Basic settings
Use these settings when configuring a mail client for an all2all mailbox:
| Setting | Value |
|---|---|
| Incoming mail | IMAP, recommended |
| Alternative incoming mail | POP, only if you explicitly want to download mail locally |
| Outgoing mail | SMTP submission with authentication |
| Encryption | STARTTLS when available, or direct SSL/TLS on the dedicated SSL ports |
| Username | The mailbox login as shown in Virtualmin, under Users, column Username; this is not always the full e-mail address |
| Password | The mailbox password |
| Authentication method | Normal password / plain text password inside the TLS session; do not enable SPA, CRAM-MD5 or other special challenge-response mechanisms |
Ports and protocol baseline
| Service | Port | Use |
|---|---|---|
| IMAP | 143 | IMAP with STARTTLS, recommended when the client supports STARTTLS cleanly |
| IMAPS | 993 | IMAP with direct SSL/TLS |
| POP3 | 110 | POP3 with STARTTLS |
| POP3S | 995 | POP3 with direct SSL/TLS |
| SMTP | 25 | Server-to-server SMTP, MX reception and internal/local relays; not the recommended client submission port |
| Submission | 587 | Client submission with STARTTLS and authentication; recommended for outgoing mail |
| SMTPS | 465 | Direct SSL/TLS with authentication; fallback when the client works better with implicit TLS |
Authentication is mandatory on ports 587 and 465. Port 25 is primarily reserved for SMTP transport, MX reception and local/internal relays.
During migrations or service reconfiguration, port 587 may temporarily differ on some servers. The target all2all policy remains: clients use 587 with STARTTLS, with 465 SSL/TLS as fallback.
Recommended approach
IMAP is recommended because mail remains available across multiple devices and through webmail. POP should only be used for specific cases where messages are intentionally downloaded to one local device.
Attention: never use POP and IMAP on the same mailbox at the same time. Strange things can happen, especially with deleted, moved or already-downloaded messages. If you want to use more than one device or mail client on the same mailbox, use IMAP only.
Webmail
Webmail is useful for testing credentials and for temporary access from a browser. If webmail works but a mail client does not, the issue is usually in the client configuration.