Mail() function simple question

[theknight]

I am running XAMPP and viewing my php files locally using the apache server it provides, however I am getting the following error:

<?php

mail('[e-mail]','Test mail','The mail function is working!');
echo 'Mail sent!';
?>

when running this php file:

Warning: mail() [function.mail]: "sendmail_from" not set in php.ini or custom "From:" header missing in C:\xampp\htdocs\MYPHP\mailtest.php on line 3

How can I resolve this?

Thanks

[theknight]

My os is windows vista

[bradgrafelman]

As the error message suggest, open up php.ini, find "sendmail_from," and set it to a proper value.