PowerMTA SMTP test — listeners, smtp-user, and submission on 587

PowerMTA defaults to accepting injection from 127.0.0.1 on port 25 without remote relay. Production setups add smtp-listener directives (for example 0.0.0.0:587), smtp-user blocks with passwords, and source entries with smtp-service yes and require-auth true.

Authenticated sources often set always-allow-relaying yes so injectors can send to external domains after AUTH. Enable allow-starttls on the listener and install smtp-server-tls-certificate for TLS on submission ports.

In SMTP Tester, use the hostname that matches your certificate, port 587 with STARTTLS, and PLAIN or LOGIN depending on authentication-method in your config. A 250 response after DATA with a PMTA message id means the message entered the queue—check PowerMTA logs for delivery status.

Recommended settings

• Add: smtp-listener 0.0.0.0:587 (plus TLS cert directives)
• Define <smtp-user> with password and linked <source {auth}>
• require-auth true on the listener source; always-allow-relaying on auth source
• Local-only testing: 127.0.0.1:25 may work without AUTH
• Restart PMTA after config changes