Microsoft Exchange 2010 permissions issue

[Guru]

Hi all,

We have an Exchange 2010 server where there is an issue with setting permissions and having them stay on there.

For example.... if we try to give user x permission to send as user y we get the following error message:

Summary: 1 item(s). 0 succeeded, 1 failed.
Elapsed time: 00:00:00

Domain\Username
Failed

Error:
Active Directory operation failed on DC02.domain.org.uk. This error is not retriable. Additional information: Access is denied.
Active directory response: 00000005: SecErr: DSID-031521D0, problem 4003 (INSUFF_ACCESS_RIGHTS), data 0

The user has insufficient access rights.
Click here for help... http://technet.microsoft.com/en-US/...=14.1.218.11&t=exchgf1&e=ms.exch.err.Ex6AE46B

Exchange Management Shell command attempted:
Add-ADPermission -Identity 'CN=Committee,OU=Misc,OU=Domain Users,OU=Headquarters,DC=doamin,DC=org,DC=uk' -User 'domain\username' -ExtendedRights 'Send-as'

Elapsed Time: 00:00:00

This fails completely, BUT if we go to the commitee mailbox in AD and edit the security permissions... set the object to inherit permissions from the parent we are then able to run the send as permission without error.

This then works and user x can send as user y just fine, but a short while later it changes back and that's where we are at now.

Any help or advice would be much appreciated.

Many Thanks,

G