I have a PHPBB 3.2.0 forum which just isn't sending any emails at all by SMTP.
I have a bunch of other scripts installed on the server, and they all send email just fine using the same SMTP configuration.
When I click "Send Test Email", the board says the test email has been sent out just fine.
Here are my SMTP settings:
USE SMTP: Yes
SMTP Server Address: localhost
SMTP Auth: PLAIN
SMTP user: firstname.lastname@example.org