> The only thing I can think of would be headers. Perhaps some are being > added, or some aren't. That did it. I added: $headers['From'] = $headers['Reply-To'] = $headers['Sender'] = $email; $headers['Return-Path'] = $email; and that worked. The headers are in an associative array because I am using drupal_mail [1] not standard PHP mail. Thanks! [1] http://api.drupal.org/api/function/drupal_mail/5