After a user's mailbox is migrated to a dedicated Microsoft Office 365 environment, the user cannot access the mailbox by using Microsoft Office Outlook or Microsoft Outlook Web App (OWA).
Additionally, the user receives one of the following error messages:
Cannot open your default email folders. You do not have permission to log on.
You don’t have permission to open this mailbox.
This problem may occur for one of the following reasons:
The NT AUTHORITY\SELF account does not have the Full Access permission and the Read permission to the mailbox.
The managed MailUser object did not have the msExchMasterAccountSID attribute present before the migration, and the discretionary access control list (DACL) of the mailbox was not updated correctly during the migration.
Note Because the following resolution involves granting a user access to his or her own mailbox, these procedures are exempt from the Authorized Requestor (AR) process.
To resolve this problem, use one or more of the following methods, as appropriate for your situation.
Manually add the permissions for NT AUTHORITY\SELF. To do this, use a cmdlet that resembles the following:
Add-MailboxPermission SMTPAddress@<the name of the domain>.com -User "NT AUTHORITY\SELF" -AccessRights FullAccess,ReadPermission