Comments on: How to Share an Email Domain Between Two Mail Systems

By: Paul Cunningham

Paul Cunningham — Mon, 10 May 2010 04:55:13 +0000

I’ve just updated the post to explain why NDRs occur in some situations when SMTP namespace sharing is implemented. The common cause seems to be due to recipient filtering.

By: JL

JL — Sat, 01 May 2010 09:49:29 +0000

I’m trying to do the exact same thing as we have 2 orgs and want mail for domainB to route via domainA and mailboxes are spilt between the 2 domains i.e. some in domainA and some in domainB. So we’ve got an accepted domain for domainB as internal relay and a corresponding connector set to relay mail to domainb via it’s smarthost. It works if we have a contact object in domainA only if not we get an unknown address 550 NDR.

Some posts I read say we don’t need contacts (like yours) and some say we need that or at least gal sync in between the 2 orgs. What gives? Even MS says you don’t need it:

http://technet.microsoft.com/en-us/library/bb676395%28EXCHG.80%29.aspx

But it won’t work unless you do.

By: Paul Cunningham

Paul Cunningham — Thu, 29 Apr 2010 01:36:08 +0000

iamme, I’ve never had a problem like you describe, it has always worked fine for me as shown in the article. I’ve never had to resort to using Contacts to handle the email forwarding.

You might be thinking of using Contacts so that user in the other domain show up in the GAL. There are other ways of syncing the GAL between orgs that don’t require you to create Contacts.

And yes, for any local recipient to receive email to a given domain you will either need an Email Address Policy to assign them addresses, or manually assign them.

However, it is the Accepted Domain that controls whether or not the Exchange org accepts mail for the domain and what it does with it, not the EAP. So the lack of an EAP doesn’t necessarily make the Accepted Domain “useless”.

It really is very simple to set up shared SMTP namespace between to orgs like this so I’m not sure why you’ve heard so many bad stories.

By: iamme

iamme — Thu, 29 Apr 2010 01:29:25 +0000

Don’t you have to have contacts in the local Exchange forest for it to forward to the target environment? I’ve heard of people doing this, it failing, and needing to create contacts that will handle the e-mail addresses that come in that will then have the forwarding address that will then use the Send Connector. And I’ve heard that you also need an e-mail address policy as well otherwise the Accepted Domain will be useless. Do you know whether these are true?

By: Paul Cunningham

Paul Cunningham — Mon, 19 Apr 2010 23:03:38 +0000

I’ve never had a problem with it, but as with all changes I suggest you schedule it for a low impact time of day and have a test/rollback plan ready just in case.

By: Exch2007Admin

Exch2007Admin — Mon, 19 Apr 2010 18:40:27 +0000

Quick question: When changing the DomainType from “Authoritative” to “InternalRelay” this will not impede mail flow in anyway will it?