It's not possible to determine your mistake without seeing your code. However, I can vouch for Mail::Sendmail, which I am using on Win2K with good results. It looks like this:

use Mail::Sendmail;
my %mail = (
            SMTP    => $SMTP_SERVER,
            To      => $EMAIL_TO,
            Cc      => 'me@my.com',
            From    => $EMAIL_FROM,
            Subject => 'testing',
        Message => $message,
           );
sendmail(%mail) or die $Mail::Sendmail::error;
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