submission configuration issues

Stephan Bosch stephan at
Sun Jul 28 00:13:47 EEST 2019

On 23/07/2019 17:13, Jean-Daniel Dupas via dovecot wrote:
> Hello,
> I'm having trouble configuring the submission proxy.
> I have configured the submission service as follow:
> submission_host =
> submission_relay_host = localhost
> submission_relay_port = 8587
> submission_relay_rawlog_dir = /var/log/dovecot/
> submission_relay_trusted = yes
> My main issue is that until I login, dovecot-submission won't connect to the backend and query the capabilities and so won't report the right capabilities.

That is true and expected. No connection to the relay server is made 
until the user is logged in.

> That mean that the first EHLO message don't get the right capabilities list.
> "
> 250-8BITMIME
> 250-BURL imap
> 250-SIZE
> "
> This list don't contains VRFY, DNS, and SIZE is not specified (all of these is present in backend EHLO response).
> After login, if I send an new EHLO command, everything is properly reported. The raw log shows that unlike what the documentation says,
> dovecot don't try to connect to the backend until the user is properly logged.
Oh, then we need to adjust the documentation. This is normal behavior.

> In my raw log I show that after I logged in dovecot-submission, the later open a connection to the backend and send a X-CLIENT command.
> Now, if I try to force the capabilities by using:
> submission_backend_capabilities = VRFY 8BITMIME DSN
> dovecot properly reports all SMTP capabilities in the first EHLO response, but it completely stops emitting X-CLIENT command to the backend
> and try to simply forward the command without authentication, which result in postfix rejecting the command with an unauthorized user error.

Yes, that is a bug. I have reproduced it here. We will look into it.



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