use strict;
my $str = 'lkffdsl@gmail.co.co';
my $regex = qr/^((([A-Za-z][A-Za-z0-9]*[\.\_]*[A-Za-z0-9]+){0,30}@[a-z]{3,15}\.[a-z]{2,5})|(([A-Za-z][A-Za-z0-9]*[._]*[A-Za-z0-9]+){0,30}@[a-z]{3,15}\.[a-z]{2}\.[a-z]{2,5}))$/p;
my $subst = '';
my $result = $str =~ s/$regex/$subst/r;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html