hello,
I am struggled to get Drupal to properly send mail for user registrations, most other CMS's provide a place to specify arguments used to get the php mail() function properly working, and provide some way to test the settings, at install time. Drupal leaves this for the admin to notice after install.
Im running Gentoo, php 5. setup /usr/sbin/sendmail arguments per apache vhost, or globally in /etc/php/apache2-php5/php.ini .
this worked for me ::
# pcw No directory listsings
# Options Indexes FollowSymLinks MultiViews
Options -Indexes FollowSymLinks MultiViews
AllowOverride All
php_admin_value sendmail_path "/usr/sbin/sendmail -t -i -f host@FQDN"
Order allow,deny
allow from 192.168.20.253
I sugest this to be added to the FAQ at http://drupal.org/node/5456