I wanted to further add to my May 11th post of when a users SIP URI is assigned to the email attribute of a security group. The net effect of this is the random ability of that user to IM all other OCS enabled users. In addition, all other OCS enabled uses are unable to IM that particular user that has their SIP URI tied to an email attribute of a security group. In my first post, my suggested solution was to remove the SIP URI for the email attribute of the security group. This solved the Communicator issue but it could have created another issue. The particular user, in most cases, needs to have his user ID attached to the email attribute of that particular security group. With my previous suggested the user would no longer receive email associated with that security group etc.. A better solution and over all best practice is to create an email alias that points to that user SIP URI and attach that new alias to the email attribute of that security group.