Envelope to 'root@localhost' not accepted

[Borisvl]

Hi,
suddenly we have problems to send emails from znuny via O365 emaill account. It works for severel month without any problem.
The communication protocol shows following error messages:

1 Kernel::System::MailQueue It wasn't possible to recover the communication for queued ID "127017". 12.09.2022 18:08:41 (Europe/Berlin)
2 Kernel::System::MailQueue Sending queued message with id '127017'. 12.09.2022 18:08:41 (Europe/Berlin)
3 Kernel::System::Email Trying to send the email using backend 'Kernel::System::Email::SMTPTLS'. 12.09.2022 18:08:41 (Europe/Berlin)
4 Kernel::System::Email::SMTPTLS Received message for sending, validating message contents. 12.09.2022 18:08:41 (Europe/Berlin)
5 Kernel::System::Email::SMTPTLS Sending envelope from (mail from: otrs@ip-92-205-62-221.ip.secureserver.net) to server. 12.09.2022 18:08:41 (Europe/Berlin)
6 Kernel::System::Email::SMTPTLS Sending envelope to (rcpt to: root@localhost) to server. 12.09.2022 18:08:41 (Europe/Berlin)
7 Kernel::System::Email::SMTPTLS Envelope to 'root@localhost' not accepted by the server: 501, 5.1.4 Recipient address reserved by RFC 2606 ! 12.09.2022 18:08:41 (Europe/Berlin)
8 Kernel::System::Email Error sending message using backend 'Kernel::System::Email::SMTPTLS'. 12.09.2022 18:08:41 (Europe/Berlin)
9 Kernel::System::MailQueue Message could not be sent! Error message: Envelope to 'root@localhost' not accepted by the server: 501, 5.1.4 Recipient address reserved by RFC 2606 ! 12.09.2022 18:08:41 (Europe/Berlin)
10 Kernel::System::MailQueue Permanent sending problem or we reached the sending attempt limit. Message will be removed 12.09.2022 18:08:41 (Europe/Berlin)

The problem seems to be the envelope. So we changed the value for Daemon::SchedulerTaskWorker::NotificationRecipientEmail from root@localhost to an valid email address (webmaster@rose.......ch) and we restarted the demaon and also the server.
Nevertheless, we continue to receive the error message "Envelope to 'root@localhost' not accepted by the server: 501, 5.1.4 Recipient address reserved by RFC 2606 !"
We use Ubuntu 20.10 and Znuny 6.3.4.
Any Idea?

Thanks in advance.

Best regards.

Boris

[Johannes]

Hi Boris,

your mail server does not accept mails to root@localhost, which is (I think) correct.

Envelope to 'root@localhost' not accepted by the server: 501, 5.1.4 Recipient address reserved by RFC 2606

My guess is: you need to modify your Setting for AdminEmail to a valid mail address.

And also I would suggest to delete the pending mails after that. Otherwise the "old" messages will trigger the error again.

see: bin/otrs.Console.pl Maint::Email::MailQueue
and check the options there.

regards
Johannes