(I'm not sure if I should continue posting my beginner-questions here, or start a new discussion. Possibly here so another beginner will find all of these?)

I installed the UNA SMTP module, entered setup info, and tried to send a test mail from there, I get "Mail send failed" when sending a test message.

I'm on ubuntu, with postfix mailer installed, I'm running

smtp-sink -u www-data -c -v -D emails.txt localhost:25 20

which listens on port 25 as an smtp server, and logs any activity requests.

When I telnet localhost 25, the smtp-link program does show log messages.

When I send a test message from UNA SMTP module, UNA is NOT communicating with the smtp server at all, I get no log messages from smtp-sink, and get the "Mail send failed" message in UNA.

Same results when I go to UNA as an non-email-verified user and press the "send the verification letter again", I get "Error occurred, please report error to site administrator.", and no activity/logs from the SMTP program (so UNA did not actually communicate with the SMTP server).

I checked several posts on the discussion list, and searched the internet, and didn't find anything that worked.

Any ideas what to check?