related to #8613 and #12007

inspired by https://forum.matomo.org/t/email-reports-not-sent-broken-pipe-errno-32/34047

Matomo uses a copy of Zend Mail that has last been updated in 2011 (in #2581)

While SMTP isn't the fastest developing protocol, a lot has changed in that time.

So instead of keeping an outdated library or reinventing the wheel, I'd recommend replacing it with a maintained, popular PHP library like PHPmailer or swiftmailer.

Bonus side effect: We would get proper error messages for hard to debug errors instead of things like fwrite(): send of 6 bytes failed with errno=32 Broken pipe.