A particular e-mail standard has to provide a few similar basic services:it must be able to identify the recipient of the message and it must be able to locate the receiver and find a route along which the message can be sent and delivered intact.

There are only a handful of important standards that are likely to be used by more than a couple of products and that will survive into the next generation of mail software. In the PC marketplace, two of the main newest standards to have emerged over the last couple of years are Microsoft's MAPI (Messaging API) and VIM (vendor independent messaging) from a consortium of vendors that includes Lotus, Borland, Apple and Novell. In the Macintosh platform are developments such as Apple's Open Collaboration Environment (OCE) whilst in the mainframe market is the PROFS standard with probably the greatest number of users of any standard. One system that is often mentioned is Novell's MHS (Message Handling System) that it is claimed is the most widely used API for LANs.

There are also other standards to be considered as all communications begin to merge into one data highway: fax messages, which can also be sent from most e-mail packages, the standards used by commercial on-line services, such as CompuServe, and finally the approved open standards defined by the CCITT such as X.400 and its global directory of users, X.500.

With this mass of standards, how do you choose the right one for your application? In...