Allow tenant admins access to logs from e-mails from their tenants

[douwezijlstra-frl]

Most of our tenant admins are IT admins who manage mailboxes for their clients. Whenever there is a potential problem with e-mail delivery, they have to contact support to check what happened to specific e-mails so we can check the delivery attempts and received messages.

It would be nice if tenants admins could see for themselves what happened to specific e-mail events from their account that we as admins are able to see.

[mdecimus]

#2710