Changing IMAP port for Dovecot

Question

I'm running Dovecot to let people access their email on my server. Unfortunately, some are on networks where they can't connect on the normal IMAP port, so I'm trying to change it. I changed the config to contain:

protocol imap {
  listen = *.1433 *.143
  ...

Then dovecot fails to restart:

Fatal: listen: Can't resolve address *.1433: Name or service not known

What's the correct way of doing this? If possible, I'd prefer to have it listening on both ports.

Alnitak · Accepted Answer · 2009-05-05T16:48:21.777

3

On my FC10 system running dovecot-1.1.10-1.fc10 the syntax is:

protocol imap {
    listen = *:9999 *:143
    ....
}

Look to see what error is being reported. If the configuration is actually correct then the most likely is 'Address already in use', meaning that some other process is already listening on port 9999.

EDIT - I see you've amended the question. The error is that you're using a '.' instead of a ':' as the port separator.

edited May 05 '09 at 16:48

answered May 05 '09 at 15:53

Alnitak

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I changed the question – Bart van Heukelom May 05 '09 at 16:24
It should be a colon, not a "." – Alnitak May 05 '09 at 16:47
Changing it to a colon helped. It works now – Bart van Heukelom May 07 '09 at 12:30

Zoredache · Answer 2 · 2009-05-05T17:05:04.577

3

I did a little research, accourding to the FAQ

Is it possible to have Dovecot imap/pop daemons listening on multiple ports?

No, not in the current stable release. But there are workarounds, eg using your firewall to redirect incoming traffic to a given port.

You can simply use iptables to redirect connections to 9999 to 143 with a command like below.

/sbin/iptables -t nat -A PREROUTING -p tcp --dport 9999 -j REDIRECT --to-ports 143

edited May 05 '09 at 17:05

answered May 05 '09 at 16:22

Zoredache

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iptables is awesome like that. – Magus May 05 '09 at 17:13
strange, the multiple port syntax in my answer seems to work fine. – Alnitak May 05 '09 at 19:21
@Alnitak, I used your syntax on my system and dovecot started, but netstat only showed it listening on one port. (deb5.0) – Zoredache May 05 '09 at 19:50
Having Dovecot listen to multiple ports for the same service is possible since version 1.1. Debian Lenny only ships Dovecot 1.0.x. – joschi Jun 01 '09 at 10:24

score 2 · Answer 3 · answered Aug 31 '15 at 16:06

With a current (2015) Dovecot version, the configuration for a different port or multiple ports is now different. You add a inet_listener ... {} section for each port. On my Debian 8 (Jessie) system, it is in /etc/dovecot/conf.d/10-master.conf:

service imap-login {
  inet_listener imap {
    #port = 143
  }
  inet_listener imap_9143 {
    port = 9143
  }
  inet_listener imap_whatever {
    port = 54321
  }
}

If it's in another file on your system, you can find it with grep -r -l 'inet_listener imap' /etc.

Seems to work on Debian Buster / 10.7 too! – MrSnrub Jan 24 '21 at 06:20 — MrSnrub, Jan 24 '21 at 06:20

Changing IMAP port for Dovecot

3 Answers3