I have an interesting problem from my perspective. I am not sure if anyone has come across this or not. Configuration. Exchange 2003 running on W2K in native mode < previous it was Exchange 2000 > Issue: Any user that is using Outlook 2000 or better can add a distribution list to the ACL permissions on his /her mailbox. Or a mailbox they have delegated rights to. What happens is that the Store will convert the DL to a security group. For example if you have a Global DL called all users the store will convert it to a global SG called All Users. Once the group is converted to a Security group the Kerberos token increases in size for everyone who is a member of that DL. I find it odd that a regular user with no permissions to modify AD security groups has the ability to do this. I am looking for a way to stop this behaviour. I know that I can educate the end user etc etc etc ..but we all know how well that goes .. I hope someone has some suggestions or Ideas. I know that this is only an issue in Native mode, also it does not work on the new query based distribution lists that Exchange 2003 offers but neither is a solution that I can use at the moment .. Thanks in Advance Rene