David,
Looking at the httpdocs, I think you are hosted on a Plesk control panel server, ie: windows shared server, I've moved the thread across to the right place

Being on Windows, there's no need of using the
sendmail function, but you can use certain
.cgi or .pl scripts to send emails through PHP, or best way use the
PHP's inbuilt mail(). What you'd need to do is to upload the
.cgi or
.pl files into the
cgi-bin folder parallel to
httpdocs & call them from your PHP scripts.
A sample script is copied into your website:
http://xxxx/php-mail-test.php please change the 'from' & 'to' address within it to yours.
You'd find few useful ones
HERE &
HERE. Let me know if you need any further info..
