#!/usr/bin/perl -w

use strict;

my $email = 'user@company.com';

# this will replace all @'s - add option of (2) to split to replace only one

print join( '\@', split( '\@', $email ) ), "\n";

# this will replace only one - add g to replace all
$email =~ s/@/\\@/;

print $email, "\n";