Submission service capabilities listing

[Dan]

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.

My question is, When does this occur? 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.

Is there a way to disable CHUNKING explicitly?


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
   }
}