Installing SMTP server in Windows XP Home Edition

Exactly what are you trying to do?  There is no such OS as SMTP server.

Are you trying to configure your Outlook Express e-mail setup?  If so, you need to know the names of your POP3 and SMTP mail servers from your ISP.  They would look something like:

pop3.myisp.com

smtp.myisp.com

Most of the time these will use ports 110 and 25 respectively, unless it is web bases then all bets are off.  Google mails uses some really strange port number for some reason.

Thank you for your response. I am learning PHP and am writing a simple PHP application to be deployed in my web page. It is a simple forms page, which would send out an email when submitted. I want to test this in my local machine. I was able to successfully install Apache web server and PHP in my machine. I have worked though the kinks of creating a forms page and validating it using PHP. The final step I am not able to test is the email part. Instructions in the PHP forum states that SMTP service should be running when I go to "Settings -> Control Panel -> Administrative tools -> Services". I am trying to figure out how to install or activate the SMTP service in my machine. Any advice would be appreciated.

SMTP service runs from an Exchange server.