The Windows implementation of mail() differs in many ways from the Unix implementation:

See:
http://de3.php.net/manual/en/function.mail.php

Search Windows Notes on this page.

(Windows only) When PHP is talking to a SMTP server directly, if a full stop is found on the start of a line, it is removed. To counter-act this, replace these occurrences with a double dot.
<?php
$text = str_replace("n.", "n..", $text);
?>

- Does anyone has a test with php and Windows 2003 Server, activate_code can`t send !?

- How can you enable / activate the users? activate_code from user is on database but no link was send?

Thanks Robert