We had a primary domain with two child domains because of limitations in exchange 5.5. we then went to exchange 2003 and migrated all the child domains into the primary, creating one domain. The problem is with one universal distribution group. Whenever anyone sends to the group they get an NDR for an account from one of the child domains. I deleted the group and created a new group with a different name and added all the valid accounts back into it. The phantom user account transferred to it! The account is not visible in ADSIEdit, nor LDP. I enumerated the member field for that group with VBScript and PowerShell – neither shows that user as a member. When we migrated, we exported up all the users mailboxes to pst files and then imported them back into outlook once they had been successfully migrated. At the time we were using outlook 2000 and have upgraded to outlook 2003 and now outlook 2007, but the phantom user is still with us. Is this an exchange 2003/active directory problem or could it be an outlook problem – rule, delegation, etc.? Thanks much for any info, clues

Software/Hardware used:
exchange 2003 sp2, windows server 2003 sp2, xp sp3, outlook 2007 sp2