Exchange 2003 2007 

I'm having some real fun on this one. 

Company1 is spinning off company2. Unfortunately for me they decided to begin using company2.com for users in company1's Exchange organization. I am pretty clear on how company1 needs to configure their SMTP connector to route mail down to me.

However, I am the last link in the chain and am unsure what i need to do to route company2.com messages back up to them and not get caught in a loop. 

I believe that the Exchange guys at Company1 planned to keep a copy of all of our users in their GAL and set their TargetAddress property to = org2.company2.com and then configure a recipient policy and connector to forward all mail down to us for those users. I am guessing that this allows them to remain authorative for company2.com but still send email down to us if the recipient matches one of our people. 

If this is the case, does it mean that I can configure a connector to route all company2.com email back to them if it cannot be delivered by my servers? This also allows my users to send email to their company2.com email addresses. It should also produce a NDR if they can't deliver.

Oh yeah, and our idea to replicate GALs got shot down so I can't use that option. :(

Any help would sure be appreciated. I have white papers coming out of my ears over here....and some of them even contradict themselves. grr.

Hi,

Which Exchange org/system is the target of the MX record for Company2.com?  I am assuming the SMTP address space of your Exchange org is org2.company2.com, is this correct? Is this also the primary address in the Default recipient policy?

The following KB article will be of use to you: http://support.microsoft.com/?kbid=321721

Basically the solution calls for you to configure an additional recipient policy. 

1. Your default recipient policy will have the primary SMTP address space of org2.company2.com and the checkbox "This Exchange Org is responsible for all mail delivered to this address" will be checked

2. The additional Recipient policy will have company2.com as the primary SMTP entry but this time the check box "This Exchange Org is responsible for all mail delivered to this address" is NOT checked. 

You will also need to change the order of the recipient policies so that the default has less priority than the newly created one, you will also need to create/apply a suitable LDAP filter for the new recipient policy so that it is applied appropriately

The procedure above will ensure your email server does not think that it is responsible for all email bound for the company2.com SMTP name space and will forward any messages out for which a mailbox/address cannot be found in your Exchange org.

If you have any further questions don't hesitate to reply to my post.

Regards