#!usr/gnu/bin/perl -w
use strict;
my $file = "pathname/to/acl/user/file";
my $user;
open (ACL,"<$file") || die $!;
while($user = <ACL>)
{ chomp $user;
  next if !$user;
  $user = "$user.mydomain.com"; #add domain for smtp
  print $user; #to get a listing
}
close(ACL);