Discourse fails to properly send an email via a local exim4 smtp server

Exim4 cant accept the email from Discourse for some reason. It appears that Discourse has design flaws or bugs that are causing this. After trying to send the initial registration email so that the admin user can be registered, the email is never received at the destination and the following error is in the exm4 log:

2021-01-21 00:39:39 H=(localhost.localdomain) [] X=TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256 CV=no F=noreply@forum.domain.com A=dovecot_plain:postmaster@forum.domain.com rejected RCPT admin@email.com: Sender verify failed

It looks like exim is rejecting the message. I think it’s because discourse is using a notification email address that exim doesn’t like.


The error message says “Sender verify failed”. This means that Discourse, which is the sender, is failing. Thus, there must be a design flaw and/or bugs in Discourse causing this.