Google changed the way their groups forward emails when the sender has strict spf/dmarc policy - to be dmarc compliant, Google started rewriting the From: and Sender: headers and changes them to 'originalsender via google_groups_address'.

This is causing major trouble to the customers.

There should be a way to modify the mailhandlers to read 'x-original-sender' header and use 'x-original-sender instead the usual From and Sender headers.