looking for any suggestions here. I'm really tearing my hair out over this:
Running Moodle 3.3.
Looking at the error logs, we had been getting an 'SMTP connect() error' on all outgoing emails since 11 Nov.
On 3rd Jan I fiddled with SMTP settings, changing them to an smtp server running on my own server. Emails worked just fine for all of 3 days before we started getting the same error.
With debugging turned on we were getting an error which said our IP was blocked/blacklisted. but the hosting provider confirmed it is not blacklisted and a simple php mail() test sends emails just fine from the moodle root directory.
More ruthless fiddling with trying about a dozen smtp servers, checking and double checking credentials and all sorts, but I cant get a single email to send.
Now debugging is not coming up with any errors at all (without any smtp settings, trying to use php mail()) but I am still getting the SMTP error in the moodle error logs and no emails are being sent/received.
I thought this might be a phpmailer issue so I replaced lib/phpmailer with other versions from 3.4 (not working at all) 3.3 latest and eventually 3.1. No luck whatsoever.