With authenticated SMTP, you can administer who can send E-Mails through your web server. With control such as this, you could set up your network so that it allows users who are not located inside to send E-Mail. You may end up with your network as sending anything from inside and authenticated from outside. This means that roaming users are in good hands. It also means you can trace the messages to the user who logged in (if they authenticated). For example, the logs may look like (the unauthenticated entry being first, and the major differences in bold) : You can accomplish this using the following entries in the Exim configuration authenticators section (see the Exim Documentation for more information). In short, these authenticators are required to work with most clients on authenticated SMTP. Note, Outlook Express uses the LOGIN authenticator, while Netscape/Mozilla uses the PLAIN authenticator. The following implementations use a database to house the passwords, encrypted by the crypt() function in Unix. You can do plain passwords, but that gets dangerous with security holes. In fact, you can turn on cryptographic functions to make this better. But, our example : Notice the two differences between the authenticators. The first, is the PUBLIC NAME, which will resolve to PLAIN, and LOGIN (see above description for which is used by what software).

The second difference, is the LOGIN uses $1 for the username and $2 for the password, while PLAIN uses $2 for the username and $3 for the password. This is because the AUTH PLAIN protocol supplies the username and password on a single line, while the AUTH LOGIN supplies the username after prompts, where the remainder of the line is blank (so $1 would be blank).

Once these authenticators are configured to your needs, just add the This will turn on advertising for all hosts trying to send E-Mail. Now, you can configure your clients to use authentication for SMTP, and it should work fine! Congratulations!