E-mail spoofing is a technique that enables a user to send e-mail in which the sender address and other parts of the header are forged, in order to appear as if the e-mail originated from a different orgin.

E-Mail spoofing is used for a variety of reasons, many of which are unscrupulous. Spammers, phishers, botmasters, and identity thieves all use e-mail spoofing techniques.

By changing the properties of the e-mail header, such as the From, Return-To and Reply-To fields, users can make the e-mail appear to be from a sender of their choosing.