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pwashburn1224

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Rewrite From: address field with Exchange 2010 Transport Server

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:
DistributionList1@domain.org
    Someone@yahoo.com
    SomeoneElse@gmail.com
    AnotherSomeone@aol.com

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.
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Avatar of Jamie McKillop
Jamie McKillop
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pwashburn1224

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I'm running Exchange 2010 on one Win2008 R2 server.  So all roles are on the one server.  I see Hub Transport under both Organization Configuration and Server Configuration in EMC.

Doesn't that combine several roles including the Transport Server role?  I know I've played with both Send Connectors and Receive Connectors there.
The Edge Transport server is a separate role that is installed on a dedicated server. If you a have a single combined role server then you do not have an Edge Transport server. There is a difference between the HUB transport and the EDGE transport.

-JJ
Was just going to edit my post to "Edge Transport" rather than "Transport Server", but was locked out while you were making your comment :)

Yup, only a single server in this organization, so no Edge Transport server.  

So I guess that means I'm hosed in this case via that solution.  

Any other possible solutions?

I wouldn't think we're the only ones having problems with DMARC and messages going out via Exchange Distribution Lists.
You've encountered one of the problems of adding external recipients to distribution groups. I'm afraid I don't have a solution.

-JJ
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