In my forest I have 4 domains, an empty root domain and 3 child domains. Corp, DomainA.Corp, DomainB.Corp, and DomainC.Corp. There are 5 sites (we'll call them Site1, Site2, Site3, Site4, Site5), each with its own Exchange administrative group and Exchange server. All DCs in the forest are 2003 and all Exchange versions are 2003. The forest and child domains are 2000 native mode.
Site1, Site2 and Site3 are all in the DomainA.Corp domain. Site4 has DomainB.Corp and Site5 has DomainC.Corp.
When I create a distribution group or make a security group mail-enabled, the group seems to get the recipient policy for Site1. Like the SMTP address it is assigned is groupname@DomainA.Corp and the administrative group is Site1. It isn't a big problem for Site2 and Site3 since they're the same domain, but the ones for Site4 and Site5 have to be manually changed.
Figure A on this page shows them getting the option to pick the admin group when they are establishing the email address, but on that page I don't get that drop down box. Maybe that was just an Exchange 2000 thing that was removed in 2003 though.
Am I missing something obvious here?