If you get this error:
- install Drupal SMTP Module: http://drupal.org/project/smtp
- download & extract phpmailer to modules/smtp/phpmailer : http://phpmailer.sourceforge.net/
- dont forget to rename "modules/smtp/phpMailer_vx.." to "modules/smtp/phpmailer"
- Turn SMTP on : admin/settings/smtp
- double check your auth-settings