Attempts to forward to external emails results in user unknown bounce

I’ve followed the instructions in CyberPanel docs and set up mail forwarding from my email at that is housed on CyberPanel and Centos 8 on DigitalOcean to forward to two external addresses: and

When I send an email from an external address, say to the, both forward addresses don’t work, only receives an email but both forwards bounce.

The undelivered error message I’m getting back at reads as follows:
This is the mail system at host

I’m sorry to have to inform you that your message could not
be delivered to one or more recipients. It’s attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

               The mail system (expanded from user
unknown (expanded from user unknown

Is this a known issue? What could be causing it?

Any help in getting to the bottom of it is greatly appreciated.


Hi @sleyzerzon Can you solve the problem?