Solaris™ Operating Environment Boot Camp

Mail Protocols

Now that we've seen how the mail process works, let's look at some of the protocols that are used to tie everything together. First we need to be aware that while there are a number of different mail protocols, we are primarily referring here to what's commonly known as “Internet mail”—that is, TCP-based Simple Mail Transfer Protocol (SMTP) mail.

We'll also briefly describe some of the “surrounding” protocols that help to make mail retrieval possible on non-SMTP servers. While these aren't bundled with the operating system, they are used often enough to make it worthwhile documenting them here.

Simple Mail Transfer Protocol

Let's start with the SMTP. The program that uses this protocol is named /usr/lib/sendmail and is the main ...