Hi,

I also encountered this issue after updating from dovecot 2.3 to 2.4 (Debian upgrade to trixie). I managed to get dovecot working and thought I'd share the info.

In my case the submission-login config looked like this:

service submission-login { inet_listener submission { port = 465 ssl = yes } }

This worked in v2.3 but yielded the "|Error: duplicate listener: 465:*|" error message in v2.4.

I managed to fix it by renaming the inet_listener to "submissions" (note the trailing s).

I think that dovecot has some sort of default config for the submission-login service. I found this in the dovecot code that seems to point in the same direction: https://github.com/dovecot/core/blob/main/src/submission-login/submission-lo... This default config contains an inet_listener called "submissions" on port 465 with TLS enabled. When you configure an inet_listener that is not named "submissions" and put it on port 465 this clashes with the default listener. Though I am not really sure if that is correct and I don't claim I really understand what that code does so take this with a grain of salt.

I did not find any mention of this in the documentation. If dovecot actually injects some default config I think this should be prominently mentioned somewhere in the docs.

There is also a default "submission" listener for non-TLS traffic on port 587. I explicitly disabled this by setting the port to 0 (this is documented here https://doc.dovecot.org/main/core/config/service.html#inet_listener_port). If this is not done, dovecot will also listen on port 587. My full submission-login config now looks like this:

service submission-login { inet_listener submission { port = 0 }

  inet_listener submissions { port = 465 ssl = yes } }

Hi,

I also encountered this issue after updating from dovecot 2.3 to 2.4 (Debian upgrade to trixie). I managed to get dovecot working and thought I'd share the info.

In my case the submission-login config looked like this: service submission-login { inet_listener submission { port = 465 ssl = yes } } This worked in v2.3 but yielded the "Error: duplicate listener: 465:*" error message in v2.4.

I managed to fix it by renaming the inet_listener to "submissions" (note the trailing s).

I think that dovecot has some sort of default config for the submission-login service. I found this in the dovecot code that seems to point in the same direction: [1]https://github.com/dovecot/core/blob/main/src/submission-login/submission-lo... This default config contains an inet_listener called "submissions" on port 465 with TLS enabled. When you configure an inet_listener that is not named "submissions" and put it on port 465 this clashes with the default listener. Though I am not really sure if that is correct and I don't claim I really understand what that code does so take this with a grain of salt.

I did not find any mention of this in the documentation. If dovecot actually injects some default config I think this should be prominently mentioned somewhere in the docs.

There is also a default "submission" listener for non-TLS traffic on port 587. I explicitly disabled this by setting the port to 0 (this is documented here [2]https://doc.dovecot.org/main/core/config/service.html#inet_listener_port). If this is not done, dovecot will also listen on port 587. My full submission-login config now looks like this:

service submission-login { inet_listener submission { port = 0 }

 inet_listener submissions {
   port = 465
   ssl = yes
 }

}

References

Visible links

1. https://github.com/dovecot/core/blob/main/src/submission-login/submission-lo...
2. https://doc.dovecot.org/main/core/config/service.html#inet_listener_port