Ran into problems sending mail. Error: 550

[drusso1]

This might be a problem with our domain email server config, but if so, I don't know what configuration is required.

The error log for our SMF 2.1.4 forum includes repeated instances of this message:

"Ran into problems sending mail. Error: 550 Message rejected. gmail.com is not currently owned by sender."

I get the same error if I try to send a test message. I don't think the forum admins are getting emails from the forum any more. We used to some months back.

I have specified the following email in the Email setting for the site::

Mail type: SMTP
SMTP server: localhost
port 25
Email: [email protected]

[Aleksi "Lex" Kilpinen]

Probably your forum webmaster email does not match your SMTP account, and this is a no no. You can not use @myowndomain.tld SMTP to send mail "from" gmail.com

[drusso1]

Thanks, Lex. I selected PHP as the send method, and that seems to have solved the issue well enough for us.

[Aleksi "Lex" Kilpinen]

I would have strongly suggested just changing the webmaster email address instead, SMTP is basically always the preferred sending method.
If you still use a gmail.com sender address, it's going to get blocked as spam even if PHP does send it out. To avoid that, you would need to use actual gmail SMTP servers.

[shawnb61]

We have started seeing some SMTP configurations that do live edits on emails leaving the SMF mail queue.  Normally, they queue up on the SMTP server side.

One of the errors we've seen is a 550.   

Fix coming in 2.1.5.

More details up on GitHub:
https://github.com/SimpleMachines/SMF/issues/7787
https://github.com/SimpleMachines/SMF/pull/7788