Transmission of messages composed on one or more input devices to a single or multiple recipients by means of one or plural communication modes is facilitated. Such communication modes may include conventional or wireless telephone, facsimile transmission, pager, e-mail, postal mail or courier. An application program interface (API) mediates between remote applications requesting messaging functions and a message server that actually implements these functions. The API is capable of processing high-volume requests for message routing, status information, and various other functions on an automated basis, enabling businesses to make routine use of these functions.