bool mail(string to, string subject, string message, string [additional_headers]);
Mail() automatically mails the message specified in message to the receiver specified in to. Multiple recipients can be specified by putting a comma between each address in to.
Example 1. Sending mail.
If a fourth string argument is passed, this string is inserted at the end of the header. This is typically used to add extra headers. Multiple extra headers are separated with a newline.
Example 2. Sending mail with extra headers.