Non profit organization using Exchange 2010
Getting a lot of "Message rejected due to DMARC policy" NDR's back
We use Exchange 2010 Distribution Lists extensively with most entries on them being Contacts in Exchange/AD going to personal email addresses (AOL, Gmail, etc.)
Here's what a sample distribution list looks like:
A member of the list might Reply to an email sent from the list. The reply would be to DistributionList1@domain.org and "From" that person, say Someone@yahoo.com.
DMARC is in play now and it looks like Yahoo has set theirs to "Reject" and that's the reason I'm getting the NDR. The "From" field in the email show Someone@yahoo.com and "Resent" from DistributionList1@domain.org.
Looks like the "From" address is the problem with DMARC. The receiving SMTP server looks at the From address, looks at our IP as we sent it and sees using DMARC/DKIM/SPF that we aren't an authorized email server for "@yahoo.com". And I get the NDR email in return.
It looks like I can rewrite the "From:" address using Exchange 2010 Transport Server role to be from our domain. As in From: DistributionList1@domain.org. Then our DMARC policy and DKIM and SPF would all be happy.
So, how do I rewrite the From: address with Transport Server? I guess I would see the incoming email arriving at our Exchange server with To: showing DistributionList1@domain.org and then rewrite the From: to be From: DistributionList1@domain.org before sending it out of Exchange.
I can't quite figure it out looking at the Microsoft TechNet hits I get in Google.
Some initial help and steering would be appreciated.