You may not need to set one up, if your ISP provides you with a POP3 email address, chances are they have an outgoing SMTP server that you can use. Look up your ISP's website, or contact their tech support, and look up information regarding 'setting up your email'. Find out the address of their SMTP, usually mail.yourisp.com, and then you just need to add this into your PHP.INI file, and wala. Much easier than setting up sendmail or some equivalent.
-m