Hello dear community,
I have the following problem:
Due to the requirements of some old systems in my network, I have set up authentication via SMTP on port 25.
/root/mailcow-dockerized/data/conf/postfix/main.cf
smtpd_tls_auth_only = no
/root/mailcow-dockerized/data/conf/postfix/master.cf
smtpd_sasl_auth_enable=yes
Unfortunately, I receive the following error message when authenticating via port 25:
NOQUEUE: reject: RCPT from unknown[IP-ADRESS]: 504 5.5.2 <SRV-MS01>: Helo command rejected: need fully-qualified hostname; from=mail@internaldomain.de to=mail@externaldomain.de proto=ESMTP helo=<SRV-MS01>
If I connect via TLS/SSL, the problem does not occur!
I then added the following lines to main.cf:
smtpd_helo_restrictions =
permit_mynetworks,
permit_sasl_authenticated,
reject_invalid_helo_hostname,
reject_non_fqdn_helo_hostname,
permit
I have also adjusted the following setting:
smtpd_helo_required = no
I then restarted all services and the system, but I get the same error: need fully-qualified hostname
What do I have to do so that I do not need a fully-qualified hostname via port 25?