Take Control of Apple Mail, 3rd Edition

Learn about Email Protocols

The word “protocol” may sound complicated, but it’s just a way of describing how your email program (in this case, Mail) talks to a mail server. If you know a few basics about email protocols, you’ll have an easier time understanding Mail’s interface and solving problems.

Although you may not be aware of it, most email accounts involve two separate systems—one for receiving and another for sending—and these often use entirely different servers. You probably use the same username and password for each, but behind the scenes, each account may function as two separate accounts:

• Your incoming account fetches email from your mail server and delivers it to you using a mail delivery protocol—such as POP ...