Started happening today, when posting it keeps showing as if it tries to post, but never completes. When I check the board, it is already posted.
https://www.translatum.gr/forum/index.php
Php version? Does it happen in Curve?
I'd start by looking at all of those browser console errors...
It was fixed when I changed to Mail type from SMTP (it was using port 465 due to Directadmin changes).
The Exim configuration is updated to not allow users to perform SMTP authentication on TCP port 25. This means email clients will not be able to use port 25 for sending emails. TCP port 25 will be exclusively used for communication between mail servers, and clients will have to use 587 or 465 ports.
https://docs.directadmin.com/changelog/version-1.676.html
Did you change the type from SMTP to PHP, or from PHP to SMTP?
More & more servers are rejecting PHP these days. SMTP is strongly recommended.
I changed from SMTP to PHP as for (probably the above reason) it stopped sending notifications. Then I tried the 465 port and the posts never reached the end... So not sure what settings to try now.
I think you need to check with your host for the proper settings.
The only undocumented nugget I've encountered with SMF is that you have to prefix the host with ssl://.