I've observed this only recently: after creating a new mailbox, if several other users are givenfull access to the mailbox,some of those newly added users "disappear" the next time Icheck in"Manage Full Access Permissions..." Typically it takes just several minutes for this to happen.The work around is to send an email to the newly created mailbox before adding users in "Manage Full Access Permissions..." or to get the user to logon to the mailbox first and then adding permissions for the other users.I suspect this is because the permissions areon the DB rather than AD and the mailbox in the DB isn't really there until the owner either logs in or an email is delivered to the mailbox.Not a real problem but would be interested if anyone else has come across this behaviour.cheers,soon

You may be seeing this because the permissions are assigned on the E2K7 administrative group and the mailbox is inheriting those permissions.Jim McBee - Blog - http://mostlyexchange.blogspot.com

Right, a mailbox doesnt get it's perms until its "created" by receiving a message or the user logging on to it.This KB hints to that issue:http://support.microsoft.com/kb/272153/en-us"Mailbox Rights for New Users Shows Only Self"

Thanks for the replys. From the info you gave me I found http://support.microsoft.com/kb/304935which describes the msExchMailboxSecurityDescriptor attributeWith this understanding, I created a new mail box in EMC and delegated Full Access to another user from "Manage Full Access Permission..."This change took and was seen in msExchMailboxSecurityDescriptor.Delegated Full Access to several users from "Manage Full Access Permission..." and only the last user took. This was reflected in msExchMailboxSecurityDescriptor.StartedADU&C onan EX03 box and viewed the mailbox rights of the new mailbox. The users that were successfully added using EMC were shown to have Full Access.Still in ADU&C, I added several users with full access to the mailbox and all were shown in msExchMailboxSecurityDescriptor but none of these newly added users showed up in EMC "Manage Full Access Permission..."Sent mail to the new mailbox and all the users in msExchMailboxSecurityDescriptor and inherited permission users are displayed in EMC "Manage Full Access Permission..."Repeated theabove actions andcorroborated results.cheers,soon