Always start with:

use warnings;
use strict;
[download]

This will catch half (or more) of the mistakes you're likely to have in any piece of code.

Next: are you going to do the same thing for every kind of spam? If so, you could use just one single regular expression to catch them all.

OTOH, remember that spammers are nowadays including deliberate spelling errors so that this kind of method doesn't work...