WP-Contact Form

I’m having almost the same problem with this plugin as I did with the email notification (previous post). I have a contact form on my site: http://www.cheeseballonline.com, and when I tried testing to send a comment to myself through the form, this is the error that I get:

Warning: mail(): “sendmail_from” not set in php.ini or custom “From:” header missing in C:\Sites\Single22\chomratana\webroot\wp-content\plugins\wp-contactform.php on line 133

Any ideas on how I can fix this?