Hello Folks,

I've got a problem understanding the usage of "InternalRelay" domains in conjunction with a shared mail-domain, hopefully someone can help me out:

I have the following situation:

Company A:

Exchange Server using "xy.com" as "InternalRelay" domain and a SendConnector for "xy.com" to Company B

Company B:

Vice versa, Exchange using "xy.com" as "InternalRelay" domain and SendConnector for "xy.com" to Company A

Both companies (partially) use "xy.com" as primary SMTP addresses for their mailboxes.

Now - to my understanding - when a user in Company A sends a mail to a non-existing Mailaddress in the "xy.com", this mail will generate a mail loop, as both exchange servers forward the mail to each other (--> please correct me if this assumption is wrong! i didn't have the possibility to practically test it) until one of them breaks the loop by discarding the mail with an NDR.

To avoid this, i've tried to configure recipientFiltering (setting RecipientValidationEnabled and additionally "AddressBookEnabled" on the "xy.com" AcceptedDomain) on Company A's Exchange Server (and creating Contacts in Company A for every valid xy.com recipient in Company B). However, Exchange is still forwarding every unknown xy.com Recipient to Company B and doesn't reject invalid recipients by itself as i thought it would.

The "Recipient filter" Transport agent is enabled of course.

I'd be glad on any hint you can give me on this topic.

Thanks in advance,

Juergen

Hello Folks,

A tiny little comment on technet (https://technet.microsoft.com/en-in/library/bb676395%28v=exchg.141%29.aspx) states:

"For mail looping, you can create contacts for the users present in other domain using any GAL sync tools (eg: ILM, Qwest etc).

When you have contacts created, you can leave the domain as authoritative domain and if the mail is destined to that contact, it will use a matching address space connector and send it to the other domain if you have specified that other domain server as the smart host in that connector."

So I've adopted my test-setup and reset the "xy.com" domain to an "authorative" AcceptedDomain and voila, everything works as expected:

* on-site mails to "*@xy.com" are delivered locally

* off-site mails to "*@xy.com" are delivered through the appropiate send-connector if an AD-contact exists

* non-existing mail addresses are NDRed by the local Exchange

Beside the fact, that Company A and B need to keep their AD Contacts for each other up to date, does anyone see any disadvantage or even failure-potential in this setup?

Thanks in advance,

yours,

Juergen