use strict;
use warnings;
use MIME::Lite;

# from the link you gave
sub get_login_env {
  local %ENV;
  my $shell = shift || (getpwuid($<))[8];
  my $env = `echo env | perl -e 'exec {"$shell"} -sh'`;
  if (wantarray) {
    my @pieces = ( $env =~ m/^(.*?)=((?:[^\n\\]|\\.|\\\n)*)/gm );
    s/\\(.)/$1/g foreach @pieces;
    return @pieces;
  }
  else {
    return $env;
  }
}

%ENV = (%ENV, get_login_env());
my $mailvar = $ENV{'TESTMAILUSRS'}; 
my @mailUsers;
my $msg = new MIME::Lite();
$msg->build(
  From            =>    'us@here.com',
  Subject        =>    'Email from perl via cron',
  Type            =>    'text/html',
  Data            =>    'testing',
    Debug            => 1

);

for (split /[\s\n]/, $mailvar){
    if($_){
        $msg->add(To    =>    $_);
    }
}

eval { $msg->send };
die "MIME::Lite->send failed: $@\n" if $@;
[download]

How does it fail for you? Does sh pick up the correct environment? Maybe you set some environment variables in another rc file, or in .profile or .kshrc. Start some debugging.

I don't get the email sent, I don't see an error message in the mailbox for the user cron is runing as. If I use the data dumper module and add print Dumper(\%ENV); to the code I can see the env vars when running it interactivly. Can you please let me know how I can debug this issue? Thanks