I 've removed a mailbox from are leaved user, then reconnected it to a new user account. i can use this new user account to send out mail by outlook(mapi) and iphone, but when i using OWA, i got the error message "You don't have the permissions required to send messages from this mailbox" when i click Option button in OWA it show "You don't have permission to open this page. If you're a new user or were recently assigned credentials, please wait 15 minutes and try again. If the problem persists, contact your administrator." I already add full management permission and send as permission to that new user, but still can't work

Hi Can you post your version of exchange? Can you compared attributes between your "owa error " mailbox account and "normal" mailbox account ? run get-mailbox user |fl someone suggests to run Set-Mailbox "user" -RoleAssignmentPolicy "Default Role Assignment Policy". You can read this article.Please 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.