"Return-Path" domain different than "From" domain triggered only a quarantine

[Gambix]

Hi all,
today a user asked me if she should trust an email. On the email box it was listed as coming from their own domain (noreply@userdomain.com).I took a look and saw that on the left the sender was the Return-Path and that one had a different domain. The user had taken a look only at the one on the email text box. I did not think it was worth getting into the details of the difference in Return-Path and From and Sent on behalf of, etc ...

Am I wrong in considering that an mail sent on behalf of a user X/domainA by user Y/domainB is unlikely if not weird?

Can some config or rule discard these messages right away possibly even rejecting them at the perimeter?

 

[LeFred]

The Return-Path sender must be verified against SPF rules of that domain.
The From-header sender should be verified against DKIM signature of that domain.

domains of return-path and From-header can be different.