Can't send email via SMTP in Postfix/Ubuntu, but can receive it fine using IMAP/POP3

Question

I'm running Ubuntu, have Postfix installed. Followed https://help.ubuntu.com/community/Postfix to the letter.

I can receive email via IMAP and POP3 perfectly in Thunderbird. But when I try to send emails, both Outlook and Thunderbird keep saying I've entered the wrong login. I enabled SMTP-AUTH and TLS.

I tried changing the ports from 25 to 587, but it didn't change anything so it's not an ISP issue.

Does anyone have any suggestions? Been trying to fix this for like 6 hours. Thanks!

Answer 1

Outlook Express (don't remember with full Outlook) does not support TLS. It only supports SSL. You might check to ensure you have SSL enabled on your SMTP server.