The mail service this house sends through, and the act of sending again. A named tool, and a plain verb.
Re- (Latin, again) attached to send, from Old English sendan, from Proto-Germanic sandijan; to resend is to send the same thing a second time, whether by a hand, a wire, or the mail service that borrows the plain verb as its name.
The mail service this house sends through, and the act of sending again. A named tool and a plain verb sharing one root, both about the same message reaching its destination a second time.