I am having an issue that is occurring Intermittently. Users who try to "Send As" a shared mailbox are getting NDR's saying they do not have permissions. The Weird part is that this issue resolves itself with no changes, but can come back just as fast. This is happening to many users trying to send as Many different shared mailbox's across multiple exchange servers. The permissons are correct because most of the time the Users can "Send As" with no problems. No Updates have been installed. Has anyone ever came across this behavior before?

Are you sure you're not running into issue below? Are these users in any protected groups? The Active Directory directory service has a process that makes sure that members of protected groups do not have their security descriptors manipulated. If a security descriptor for a user account that is a member of a protected group does not match the security descriptor on the AdminSDHolder object, the user's security descriptor is overwritten with a new security descriptor that is taken from the AdminSDHolder object. The Send As right is delegated by modifying the security descriptor of a user object. Therefore, if the user is a member of a protected group, the change is overwritten in about one hour. The "Send As" right is removed from a user object after you configure the "Send As" right in the Active Directory Users and Computers snap-in in Exchange Server http://support.microsoft.com/kb/907434James Chong MCITP | EA | EMA; MCSE | M+, S+ Security+, Project+, ITIL msexchangetips.blogspot.com

Thanks for the reply James. I did come across that article and had some hopes that it would resolve my issue, but Our permissions are not being removed. They stay intact and the issue resolves itself on its own, but does come back.

Can you check your Exchange app event logs and see if you're running errors similar like below? Event ID: 9646 Type: Error Source: MSExchangeIS Description: Closing Mapi session "/o=Organization/ou=Administrative Group/cn=Recipients/cn=user" because it exceeded the maximum of 250 objects of type "objMessage". James Chong MCITP | EA | EMA; MCSE | M+, S+ Security+, Project+, ITIL msexchangetips.blogspot.com

I do have some, but they seem to all be for a couple different users. They do not mention closing the mapi session though. Event ID: 9646 Type: Error Source MSExchangeIS Description: Mapi session "User INFO" exceeded the maximum of 500 objects of type "objFolder" Thanks

Hi morriz1, This warning may be caused by improper client design or unusual client usage patterns. Please refer to this document: Exchange Event ID 9646 http://www.microsoft.com/technet/support/ee/transform.aspx?ProdName=Exchange&ProdVer=6.5.6940.0&EvtID=9646&EvtSrc=MSExchangeIS&LCID=1033 Here is a thread about Event ID 9646, hope it help: EventID 9646 - exceeded the maximum of 500 objects of type 'objtFolder' http://social.technet.microsoft.com/Forums/en/exchangesvrgeneral/thread/36c11ba1-e779-4ee3-bea6-6ddf07c9e2c8 Thanks, EvanPlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Are you sure you're not running into the conflict between "Send as" and "Send on behalf of" permissions?

Hi morriz1, Did you actually find a resolution to this? We appear to be having the same problem started a couple of weeks ago where people will intermittently lose the right to "Send As" but the permission is still present within AD. Then around an hour later they can "Send As" again. Been searching everywhere and looking at everything but its got me a bit stumped. Can you shed any light on this? Thanks