I have followed the Perfect Server Setup for Ubuntu 7.04/7.10 several months ago. Postfix is relaying automatically generated email from Joomla (through PHP mail function) to almost all mail providers except Hotmail. The message is kept in queue and never sent. Here's an example: postconf -d outputs the following (verbose alert!!): Finally, i have found some valuable info regarding the new anti-spam policies deployed by some global providers, like hotmail (http://www.compassdesigns.net/joomla-blog/Joomla-Confirmation-emails-to-hotmail-and-aol.html): Thanks, Nuno.