[fatal] SMTP -> ERROR: MAIL not accepted from server. Code: 550 Reply: 550 5.7.1 Client does not have permission to send as this sender
[fatal] Email delivery Failure:array
The following address failed: ***.testmail@gmail.com

Hi there

I have email setup with our domain name etc working well. campaihns are sending everything, but the moment i load a new imbound email to be able to send as someone else - I get these errors. and mails do not go out. stuck in que?

Please help.

Linux
Version 6.1.4 (Build 5822)