I've run into an issue that I can't figure out and any help or direction would be wonderful. Up until about 2 weeks ago we were able to assign send as permissions without issue, now in the security tab in AD unless we go in and give them full access the permissions do not stick. If you select send as and hit applyand close, when you reopen the option is cleared again. Also, people are unable to do "send as" from some accounts that are hidden others work fine. We have made sure that they have the currect offline address book, and have left the box open for 24 hours to resolve...But the second we hide it, it give "You do not have permissions to send on behalf of" errors. this only occurs when they have it openned as an additional mailbox. If they have the box loaded as a second profile everything works fine. Note: Even with domain admins having fuill permissions to every box in our exchange server...Random boxes that are hidden are still giving "Send As" errors even to us. I know this sounds all over the place...But it would be easy for me to nail down if it was at all consistant. Just found a person who can do a "Send as" to me from an account...But get denied when they try to send to other admins. Thanks for the help

Did you install SP2 and then this issue started happening? http://support.microsoft.com/kb/895949