In the logs, the sender sees the following:
to=<me@mydomain>, delay=00:25:14, xdelay=00:05:03, mailer=esmtp, pri=349788, relay= [myip], dsn=4.0.0, stat=Deferred: 421 4.4.2 myservername Error: timeout exceeded(Reason🙂
I don’t see anything from this domain in my logs. Added to the white list in rspamd, did not help