zoldos wrote: ↑
Sun Sep 15, 2019 9:30 pm
Whereas phpBB doesn't even send it at all (it doesn't even get to Mailgun, despite all domain settings being correct). I also have a simple PHP script that I wrote which basically sends out e-mail via the PHP mailer function, and this works perfectly too.
I also tested all this on PHP 7.0.33.
The code path is so vastly different between "Use SMTP server for email: Yes" versus "No", its pretty difficult to project that "one issue" is causing both of them to fail. But could certainly be two separate issues.
The screen shot(s) of the ACP Email Settings page, as well as anything you're getting reported to the phpBB Error Log in the ACP Maintenance tab, are the first place to start looking for clues, as Mick requested.
Certainly good to have the server set below PHP 7.3.x now, and also to know that the independent PHP-based mailer script works from the same server.
When you tested the PHP mail script to exercise the "call PHP mail() function" path, are you specifying exactly the same email for the "From:" email, as is specified in the ACP Email Settings configuration for "Contact email address:" and "From email address:"? Since I assume the MailGun service gives you an externally-hosted mailbox, and the local sendmail configuration and/or the local mail servers might not be happy about trying to send with a firstname.lastname@example.org