[packman] Improving list deliverability

[Marc Schiffbauer]

Hi all,

a mailman setting which I think was long overdue, has now been enabled: 
If you send from a domain with DMARC Reject/Quarantine policy, the From: 
header will be updated to the lists address with your sender address 
being in the Reply-To: header.

This should fix some deliverability problems I have been made aware of 
recently.

Please let me know if some of you still see issues, thank you!

-Marc