Using external SMTP server

Nic · January 18, 2026, 6:38pm

Hi there, I am new to Axigen and have just installed it on Ubuntu. I am using this primarily as a backup server for my emails. It successfully pulls my emails from a dedicated POP3 account where the emails I wish to archive/backup have been forwarded. That is the crucial bit and this also allows me remote access when I am travelling to archived mail. This is setup at home using my ISP which does not provide Static IP address so I am reliant upon DDNS (which works well for the above).

However, I would very much like to be able to send/forward email when I am away from home and most servers block all Dynamic IP addresses. I am trying to configure a relay to my mail hosting provider but what I have doesn’t seem to be working. I have setup my provider in Outgoing Delivery Settings and also completed authentication but the logs show:

2026-01-18 15:12:15 +0000 08 chancel SMTP-OUT:00000007: Relay mail 2F218B: connecting to 65.20.50.51:465
2026-01-18 15:12:15 +0000 08 chancel SMTP-OUT:00000007: Relay mail 2F218B: connected to 65.20.50.51:465
2026-01-18 15:12:46 +0000 04 chancel SMTP-OUT:00000007: AUTH LOGIN rejected for domain <localdomain> with code 535 (invalid user ID or password)
2026-01-18 15:12:46 +0000 08 chancel SMTP-OUT:00000007: Start sending mail 2F218B
2026-01-18 15:12:46 +0000 08 chancel SMTP-OUT:00000007: Negative reply to MAIL command: authentication required - Your email could not be sent. To fix this you must make a simple change to your email client (known as SMTP authentication). For advice visit http://www.bt.com/smtp
2026-01-18 15:12:46 +0000 08 chancel SMTP-OUT:00000007: Set recipient <postmaster@localdomain> state to RELAY ERROR
2026-01-18 15:12:46 +0000 08 chancel SMTP-OUT:00000007: Delivery attempt completed for mail 2F218B; schedule for cleanup
2026-01-18 15:12:46 +0000 08 chancel SMTP-OUT:00000007: Set mail state to SENT
2026-01-18 15:12:46 +0000 08 chancel SMTP-OUT:00000007: Disconnected from 65.20.50.51

The credentials entered are correct but the sending fails. Any advice would be much appreciated.

florin.burada · January 21, 2026, 11:45am

Hello @Nic ,

According to the log lines you provided, the message is being rejected by the relay server due to missing SMTP authentication, which is mandatory:

authentication required - Your email could not be sent. To fix this you must make a simple change to your email client (known as SMTP authentication).

To fix this, you will need to add the username and password for the relay server in the Outgoing Delivery Settings from Webadmin → Security & Filtering → Acceptance & Routing → Outgoing Delivery Settings section → Authentication.

Regards,
Florin