When migrating a domain to another existing domain, how do you maintain security group permissions (share permissions and ntfs permissions) on file shares on a file share server? The security groups and users have been created on both domains already.

The best way to adderss this is to use ADMT to do the migration itself. If you simply just created new users and group on the new domain, you arent going to be able to "preserve" the permissions. The users from both domains will have different SIDs. When using the ADMT tool to migrate from one domain to another, when the user in created in the new domain, the "old" SID is stored in an attribute called SID HISTORY. Therefore, the user will be able to continue to access resources. Active Directory Migration Tool (ADMT) Guide: Migrating and Restructuring Active Directory Domains http://www.microsoft.com/downloads/en/details.aspx?familyid=6D710919-1BA5-41CA-B2F3-C11BCB4857AF&displaylang=en Visit: anITKB.com, an IT Knowledge Base.

That's about what I figured. I didn't know at first if the group SIDs could be migrated, but found that out after posting. The issue I have though, is the domain2 accounts already have email assigned to them since we migrated our exchange environment already. I'd like to migrate the domain1 accounts and groups into the domain2 objects and keep the domain1 SID history so that file shares can be preserved. Is that possible?

I assume that if you migrated Exchange already, you created an AD Connector import the information. Sounds like an NT 4 migration. If this is the case, the migrated objects should have been brought over as disabled user accounts. So if this is the case, Yes, you could still use ADMT to continue. After the accounts are migrated, there is a process you run (exchnage tools) to "merge" the two accounts together into one. Its been several years since I have worked on a migration such as this, so I am rusty. Visit: anITKB.com, an IT Knowledge Base.