I have a user (at least that's all i know of right now) that does not show up when you expand a mail-enabled security group in Outlook. The user is a member of that group when you look at the group in Active Directory. Also this happened when I expanded a distribution list the user is a member of. I found a post that said the user's primary group cannot be the mail-enabled group and this user's primary group is Domain Users (which is not mail-enabled). I haven't been able to find any other articles about this situation. How do i get the user's account to show up in these mail-enabled security groups and distribution lists?