http://support.microsoft.com/kb/907434 This is really an AD issue, not Exchange. If you are mail-enabling an account that is a member of an elevated group, inheritance is removed from that account by design. You should not be mailbox-enabling these users. If this is the case, remove them from the groups in question, and re-enable inheritance. This is especially important if you upgrade to Exchange 2010, things will just not work if inheritance is disabled on an account.

Hi, thanks a lot, the kb article solved my issue.

Hi, I've got a weird issue - when I set "send as" privileges on a mailbox they are removed automatically after a few minutes - nobody is able to send mails via the mailbox, all send-as privileges are removed. This really drives me crazy. The System is an Exchange 2007 on a SBS 2008 - maybe the sbs2008 does something weird.

Hi, This problem is due to the user has got added to a 'protected group'. Executing 'whoami /groups' will reveal it. Remove the user from the protected group and then you may resolve the issue. Regards from www.windowsadmin.info

Hi, how can I identify a 'protected group'?

Try for example this: http://support.microsoft.com/kb/817433 Method 1. -- Petri