sendmail, 4th Edition

Support SMTP AUTH

Support for the SMTP extension AUTH, as defined by RFC2554, was first included in sendmail beginning with V8.10. In this section, we show how to include AUTH support inside sendmail, how to verify that it works, and finally, how to use it with a server and with a client. First, you will likely need to:

• Download, compile, install, and configure the Cyrus SASL library.

• Build and install sendmail with SASL support included.

Depending on whether you manage a server or a client you may also need to:

• Configure your server sendmail machine to require AUTH.

• Configure your client sendmail machine to use AUTH.

Before we begin, however, let’s consider why you might want AUTH support and why you might not need it.

SMTP AUTH is intended to prevent untrusted machines from using mail server machines to send undesirable mail, such as spam. If yours is just a lone Linux box used to send and receive personal email (and you don’t travel), SMTP AUTH will probably not be of use to you on your server, but it might still be of use to you for a client.

For SMTP AUTH to have value to a server, that server must be on a network that supports laptops or other portable machines that can be removed and installed without system administration oversight, and where those machines all need to trust each other. The larger your site, the more likely it is that you will need to use SMTP AUTH as one more layer of email protection for your server. A mail gateway machine that is a frontend for many PC and laptop ...