SMTP: Helo command rejected: need fully-qualified hostname (solved)


I just installed the newest verson of DeltaChat and run into a problem with my mailserver (Mailcow):

504 5.5.2 <localhost>: Helo command rejected: need fully-qualified hostname; from=<xxx> to=<xxx> proto=ESMTP helo=<localhost>

Is there a way to tell DeltaChat to send a FQDN in the HELO phase of the connect? Would be great if I could make this work!

Thanks for any help in advance, Marc

Does your mail server have an internets resolvable domain?

sure, it’s a “real” mailserver with all bells and whistles. But it wants that the client that connects identifies itself with a fqdn in the ehlo/helo command and the question is if there is a way to tell DeltaChat to send a fqdn instead of “localhost”.

After reading the deltachat logs, I finally found out what the problem was: the SMTP authentication failed and therefore the Mailserver was rejecting the “invalid” EHLO (localhost). Postfix was configured that way, that authenticated clients can send whatever they want in the EHLO phase, but because DeltaChat was not authenticated, this check was active.

The question is now: why does DeltaChat not communicate properly, that the SMTP authentication failed?