Since iRedMail-0.9.5, SMTP auth on port 25 is disabled by default, all end users are forced to send email through port 587 (SMTP over TLS). If you need to allow insecure SMTP auth on port 25 for some reason, please follow steps below to enable it.
If you have just few clients need to send email through port 25, e.g. network printer, old network devices which don't support secure connection, you may try another tutorial instead: Allow internal network devices to send email with insecure connection
smtpd_sasl_auth_enable = yes smtpd_sasl_security_options = noanonymous smtpd_tls_auth_only = yes
smtpd_tls_auth_only = yes, it requires clients to enable STARTTLS
for secure connection, if you don't want this for some reason, please
comment it out.