In addition to the excellent leads given by footpad above, I might just also throw Regexp::Common written by Damian Conway into the mix. This module provides a number of regular expressions for everyday use - For example, from the documentation POD:

use Regexp::Common;

while (<>) {
    /$RE{num}{real}/                and print q{a number\n};
    /$RE{quoted}/                   and print q{a ['"`] quoted string\
+n};
    /$RE{delimited}{-delim=>'/'}/   and print q{a /.../ sequence\n};
    /$RE{balanced}{-parens=>'()'}/  and print q{balanced parentheses\n
+};
    /$RE{profanity}/                and print q{a #*@%-ing word\n};
}
[download]

In addition to this, Regexp::Common allows the specification and matching of {real} and {int} numbers, numbers of differing base and those separated into groups by a specified separator.

Definitely worth a look at ... TheDamian++

 

perl -e 's&&rob@cowsnet.com.au&&&split/[@.]/&&s&.com.&_&&&print'