On 13/11/2020 00:48, Dan wrote:> Hello all,
>
> I'm attempting to implement a submission server with questions in
> regards to how Dovecot handles the backend hosts capabilities. To my
> understanding, Dovecot will connect to the host specified in either
> submission_host or submission_relay_host, and gather a list of
> capabilities. Once gathered, after the client sends the EHLO greeting
> Dovecot will respond back with capabilities that the backend host is
> capable of.
The submission_host setting is not relevant to this topic. It is only
used for sending messages produced by Dovecot itself, e.g. from Sieve.
> My question is, When does this occur?
The automated part only works after AUTH. The initial EHLO is not
necessarily accurate.
You can configure |submission_backend_capabilities to set the backend
(=relay in this case) capabilities directly. In that case the backend
EHLO reply is not used.|
> Running a tcpdump with the filter set to the relay host IP, I don't
> see any traffic until after I send the EHLO command. Dovecot states
> that CHUNKING is available, but the backend host does not have that
> capability.
CHUNKING does not need backend support. The mail can be accepted using
BDAT command at the frontend and relayed to the backend using classic
DATA command.
> Is there a way to disable CHUNKING explicitly?
You cannot currently disable CHUNKING support at the frontend. Why would
you want to?
Regards,
Stephan.
>
> Thanks.
>
>
> submission_relay_host = x.x.x.x
> submission_host?????? = x.x.x.x
> submission_relay_ssl? = no
> submission_relay_ssl_verify = no
>
> protocol submission {
> ? passdb {
> ??? driver = static
> ??? args?? = host=x.x.x.x proxy=y nopassword=y port=587
> ? }
> }
>