You depend on e-mail. You couldn't get your work done without it. Yet most users (not to mention IT professionals and managers) experience e-mail as a mysterious, magical function. You write a message on your computer, you click Send, and moments later, it appears in the recipient's inbox. Poof!

E-mail happens invisibly. No creaking and groaning of IT infrastructure reminds you that e-mail delivery is actually a complex system with a lot of moving parts. Overall, that's a great success story—how many long-term IT services work so smoothly that users take them for granted? But if you have any responsibility for ensuring that the mail arrives, or for managing the hardworking e-mail administrators who do, it behooves you to know a minimum of the technology basics.

This article centres on the technology of e-mail. It doesn't go into e-mail management, corporate policies or matters that involve human behaviour. (That subject is covered in a later article.) Nor does this article address the key issues to consider in the war against spam, though spam fighting represents a huge amount of an e-mail administrator's energy (and angst) these days; another article addresses what managers should know about spam fighting.

Don't expect technical depth: This is, after all, an ABC, not the entire alphabet. Managers should, however, understand that a full conceptual explanation could easily fill 40 pages with dense technical definition; most of it is far more than I want to know, too. If e-mail is important for your business, however, you should have skilled people around who are up to the challenge.

This article covers the underlying technology (or, if you prefer, the most essential of those magic spells), so you have some idea of how the process works, and thus what can go wrong.