We have quite a few Distribution Lists in Exchange and we are finding that members that we know for a fact were in there are no missing. Has anyone else experienced this?

Hi, If users are being removed and it is for Groups that have restriction enabled - ensure that when you add a new user in the Exchange Management Console/Shell to a Group that you also update your Restricted Group settings to ensure Active Directory then doesn't remove that user. I hope that helps and should resolve your issue. Oliver Moazzezi | Exchange MVP, MCSA:M, MCITP:Exchange 2010, BA (Hons) Anim | http://www.exchange2010.com | http://www.cobweb.com | http://twitter.com/OliverMoazzezi