In Office 365, this permission allows users other than the mailbox owner to use the mailbox to send messages. After this permission is assigned to a delegate, any message that a delegate sends from this mailbox will appear as if it was sent by the mailbox owner. However, this permission doesn't allow a delegate to sign in to the user's mailbox.

In Office 365, this permission allows a delegate to use this mailbox to send messages. However, after this permission is assigned to a delegate, the From address in any message sent by the delegate indicates that the message was sent by the delegate on behalf of the mailbox owner.

A sub-domain is a domain that is part of a larger domain; the only domain that is not also a sub-domain is the root domain. For example, doit.wisc.edu and engr.wisc.edu are sub-domains of the wisc.edu domain.