I use CiviCRM (v5.20.0 on PHP 7.3.11 in Joomla) to send scheduled reminders for membership expiration. The mails are sent via SMTP. This works okay when i send a reminder to my own account so i expect it to work for all other accounts. Though I would like to see if mails are indeed sent but I don't see any logging where i could find if, when and to whom an e-mail has been sent.
Now I found an extension called Transactional Mail - Bounce and Tracking Handler and i installed it. When i try to send mail via the Job Send Scheduled Reminders, I see following error (only when the extension is enabled):
Failed to set sender: b.1.49.90b5f37ff0be023e@ [SMTP: Invalid response code received from SMTP server while sending email. This is often caused by a misconfiguration in Outbound Email settings. Please verify the settings at Administer CiviCRM >> Global Settings >> Outbound Email (SMTP). (code: 501, response: : domain missing or malformed)]
Any help would be appreciated.