My Mautic version is: 45_mautic-449
My PHP 80, PHP 8.0.29-1.1.3.cpanel
cPanel & WHM on AlmaLinux
OS: AlmaLinux v8.8.0 STANDARD kvm
cPanel Version 112.0.5
According, the Swift_MailTransport deprecated, Swift_MailTransport deprecated · Issue #866 · swiftmailer/swiftmailer · GitHub
My problem is :
See the screenshot image of a Mautic error message:
Does the latest version of Mautic bundles a PHP wrap with Swift_MailTransport?
It seems that this might be an issue with not being able to connect using TLS rather than anything with Swiftmailer which works fine in 4.x releases. Have you double checked that you are using the correct SMTP credentials here, and that the port/authentication settings are as required by your provider?
When the TLS tries to establish a handshake with the Google Firebase server, it is informed that “We do not authorize the use of this system to transport unsolicited, 220 and/or bulk e-mail.” I believe that Google is referring to the deprecated Swift_MailTransport, which is available at Swift_MailTransport deprecated · Issue #866 · swiftmailer/swiftmailer · GitHub.
Exists an email client, Mautic extension, OAuth 2.0 Client, or Mautic email API SDK.
See capatured screenshots: