Let's look at the following url:
xxx.antionline.com/showthread.php?s=&threadid=228805

The .php extention probabaly means that the pages are being parsed by the php executable. That being the case the database being used is most likley to be MySQL. And the probability is that the site is running on a [insert branding here]-x box. So the mail functionality is probably dealt with by sendmail (or something similar).

I am obviously just a 'newb' here and I have no inside track but that would be my best guess. That said however if anyone has better information than that, I too would be interested to know.

If your interested You can get php and MySQL (for win32) from my public ftp at:
ftp://195.8.181.206/Programming/php/