Perl for System Administration

Receiving Mail

When we discuss receiving mail in this section, we’re not going to be speaking of fetching mail. Transferring mail from one machine to another is not particularly interesting. Mail::POP3Client by Sean Dowd and Mail::Cclient by Malcolm Beattie can easily perform the necessary POP (Post Office Protocol) or IMAP (Internet Message Access Protocol) mail transfers for you. It is more instructive to look at what to do with this mail once it has arrived, and that’s where we’ll focus our attention.

Let’s start with the basics and look at the tools available for the dissection of both a single mail message and an entire mailbox. For the first topic, we will again turn to Graham Barr’s MailTools package, this time to use the Mail::Internet and Mail::Header modules.

Dissecting a Single Message

The Mail::Internet and Mail::Header modules offer a convenient way to slice and dice the headers of an RFC822-compliant mail message. RFC822 dictates the format of a mail message, including the names of the acceptable header lines and their formats.

To use Mail::Internet, you first feed it an open filehandle to a message file or a reference to an array that already holds the lines of a message:

use Mail::Internet;

$messagefile = "mail";

open(MESSAGE,"$messagefile") or die "Unable to open $messagefile:$!\n";
$message = new Mail::Internet \*MESSAGE;
close(MESSAGE);

If we want to parse a message arriving in a stream of input (i.e., piped to us on our standard input), we could do this:

use ...