Automating System Administration with Perl, 2nd Edition

Chapter 8. Email

Unlike the other chapters in this book, this chapter does not discuss how to administer a particular service, technology, or knowledge domain. Instead, we’re going to look at how to use email from Perl as a tool for system administration.

Email is a great notification mechanism: often we want a program to tell us when something goes wrong, provide the results of an automatic process (like a late-night cron or scheduler service job), or let us know when something we care about changes. In this chapter we’ll explore how to send mail from Perl for these purposes and then look at some of the pitfalls associated with the practice of sending ourselves mail.

We’ll also look at how Perl can be used to fetch and post-process mail we receive to make it more useful to us. Perl can be useful for dealing with spam and managing user questions.

This chapter will assume that you already have a solid and reliable mail infrastructure. We’re also going to assume that your mail system, or one that you have access to, uses protocols that follow the IETF specifications for sending and receiving mail. The examples in this chapter will use protocols like SMTP (Simple Mail Transfer Protocol, RFC 2821) and expect messages to be RFC 2822-compliant. We’ll go over these terms in due course.

Sending Mail

Let’s talk about the mechanics of sending email before we tackle the more sophisticated issues. The traditional (Unix) Perl mail-sending code often looks something like this example from the Perl ...