use strict;
use warnings;

my $address = 'myemail@whatever.com';
my $subject = 'Comments Version: $version  ID: $ID';

# backslash the @ sign in the address
$address =~ s/@/\\$1/g;

system( "mail $address -s $subject < blah6.txt" ) == 0
    or die "mail failed:  $?";