Some Outlook 2007 clients switching to wrong GAL!
Posted on 2012-09-20
We are migrating users from a legacy Windows 2003 forest to a new 2008 forest. These users need to retain access to their legacy Exchange 2007 e-mail system rather than using the new forest's Exchange 2010 platform. Full forest transitive trusts are in place.
We disable the legacy AD account, and From Exchange 2007 EMS, we disable the mailbox. Then we reconnect the mailbox to the legacy account, setting the LinkedMasterAccount attribute as follows:
Connect-Mailbox -Identity "/o=OurCompany/ou=Exchange Administrative Group (FYD11BO223SPDLT)/cn=Recipients/cn=mailboxname" -User OldForestADaccount -Database MailboxDatabase -LinkedDomainController newforestDC -LinkedMasterAccount NewForestADaccount -LinkedCredential(get-credential)
The new forest AD account already has an Exchange 2010 "stub mailbox" in place. Outlook (2007) will point to this if we allow autodiscover/configure. If we manually configure server settings, we can set the user to point to the correct legacy server & mailbox.
We received reports of NDRs being returned when a small number of migrated users were replying to messages received from Exchange 2010 users. On checking the GAL for these users, it transpired that their Outlook profile was displaying and resolving to the 2010 GAL! The only temporary fix we have found for this has been to delete the mail profile and recreate it. However, a few hours later the problem returns!
OWA works fine and this only seems to be an issue with Outlook 2007 SP3 clients. We have tried running in cached and online modes with the same results.
Does anyone have any experience/recommendations they can offer?