A business, also known as an enterprise, company or a firm is an organisational entity involved in the provision of goods and services. 

Messages distributed by electronic means from one computer user to one or more recipients via a network. 

!Note - Also used as a verb - to e-mail someone

A written, typed, or printed communication, especially one sent in an envelope by mail or messenger.

In business a salutation is a standard formula of words used in a letter to address the person being written to.