When using the mail PHP function to send e-mails one think you should not forget is the Content Type.
I had my contact form wich was sending me e-mails. When somebody was writing in spanish using: ó í the mail was broke up.
The solution is use the UTF-8 charset.
This is the way you should send an e-mail:
$headers = "From: firstname.lastname@example.org \r\n";
$headers .= 'Content-type: text/plain; charset=UTF-8';
$to = "email@example.com";
mail($to, "Subject", "Cool Message", $headers);