you could possibly try to install sendmail on your windows server (no idea how to do this... maybe using cygwin or some unofficial port ?)
Come to think of it: I know XAMPP comes with "fake sendmail for windows" (http://www.glob.com.au/sendmail/). So I entered that in PHP.INI as follows:
SMTP = localhost smtp_port = 25 sendmail_from = wikiAdmin@localhost.com sendmail_path = "D:\XAMPP\sendmail\sendmail.exe -t"
The default SENDMAIL.INI looks like this: [sendmail] ; you must change mail.mydomain.com to your smtp server smtp_server=localhost
Both $wgEnableEmail and $wgEnableUserEmail are set to true in LocalSettings.
It doesn't seem to work though; I've sent a user-to-user mail via [[Special:Emailuser]] a couple of minutes ago, but it still hasn't arrived...
-- F.
PS: I hope I'm not hijacking the Alister's thread here!?