Email Notifications - Error 33

The email notifications feature of Comodo Backup is the most important feature for me, and it does not appear to be working in version 4.2.2.15. The “send test message” works just fine in the Backup Destination (Step 2.) page, under Email, and clicking the Send test message. I successfully receive the test message.

When I click Next to go to the Backup Settings (Step 3.) page, the email notification is never filled in, so I set it to notify On Success and On Failure, and select the email profile from the drop-down list. On this page, if I click the “Send test message” button, Comodo Backup displays an error “Test message could not be delivered”.

If I continue and go through the backup, the log says the following:

“Unable to send notification email because 33”