disabling a distribution list in ms exch

Perhaps the easiest solution is to just hide it from the GAL.

You dont need to hide it, that will do nothing but make it invisible when someone is browsing the GAL, but they can still send an email if they know the address. To "disable" it, you simple go to where the Distribution group is located in Active Directory and right click on the group, select 'Properties', click on the 'Exchange General tab', and in 'Message Restrictions' click the one that says 'Accept messages only from:' From there you can enter the names of whomever you want to have access to it, if you dont want anyone to have access to it i would just enter your username or something and that will keep everyone else from using it.

Or simply go the the Distribution list, delete the email address used and click ok. You can hide it also at the same time. And when you want to use it again, just unhide it and re-enter the email address for the list and viola! That is the most simple and effective way with out messing around with rights.