One of my users just started getting NDRs, supposedly due to this error whenever he attempts to send messages to anyone outside of our domain. As far as I can tell, the issue is only impacting this single user. When I see him again, I'm going to have him try sending a message from another machine via OWA.I haven't done anything on the server side that should have any impact on his specific account. A sample part of an NDR follows. Thanks for any ideas: The following recipient(s) cannot be reached: <mailto:[log in to unmask]> [log in to unmask] on 1/27/2009 1:14 PM You do not have permission to send to this recipient. For assistance, contact your system administrator. MSEXCH:MSExchangeIS:/DC=edu/DC=msu/DC=rcpd:ourServer