Exchange administrative access to all mailboxes not working

Are you are using an administrative account that has access to all Exchange mailboxes but it’s not working?

The first thing to do is test the permissions.

1. Access OWA at https://mail.domain.com/exchange/user@domain.com where user@domain.com is the email address of the mailbox you are testing.
2. Provide your administrative credentials

If you can’t login, we can’t login.

Make sure the account is not a part of the Enterprise Administrators, Domain Administrators or any other system administrator group. By default, Exchange is configured to deny these users access to mailboxes.