Methods and systems and machine readable media for processing email and other electronic messages. In one exemplary embodiment, a method includes storing a plurality of domain names, each of which correspond to a portion of a full email address; receiving a first email; determining whether a sender address specified by the first email is within a domain specified by the plurality of domain names; determining whether the first email is authentically from an entity which controls the domain specified by the plurality of domain names if the sender address is within the domain; and presenting an indication of nonauthenticity if the first email is not authentically from the entity.