Yes, yes, it's entirely possible with Perl.

There are two options. You could write a simple daemon (to run at all times) to monitor a POP email account. Or you could have a script run at scheduled times (via crontab) to do the same thing.

If a certain email message is detected, you can do whatever your soul wishes, really. There's a number of modules that you could find on CPAN that will help you check a POP account from your script, parse messages, etc.

Your script may look as simple as this (read inline comments for more info):

use Mail::POP3Client;
  
$pop = new Mail::POP3Client( USER     => "me",
                   PASSWORD => "mypassword",
                   HOST     => "pop3.do.main" );

my $specific_email_subject = "Parse by script";
my $parser_script = "email_parse.pl";

for ($i = 1; $i <= $pop->Count(); $i++) {
  foreach ( $pop->Head($i) ) {
    if (/^Subject:\s+($specific_email_subject)/i) {
      # Special email detected!!!
      # open a 'pipe' to the script that will parse/process 
      # this email message body.
      open(PARSER,">$parser_script |");

      # send email body to the script (will receive
      # it via STDIN
      print PARSER $pop->Body($i);

      # close pipe (end 'transmission')
      close(PARSER);
    }
  }
}
[download]

(note: not tested).

UPDATE: added the sample script.

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