Complete mail header

Question

I need a set of mail headers to attach to my mail() function in PHP. I send emails with HTML in them, and sometimes services like Yahoo Mail block them. Therefo

Answer 1

    $headers  = "From: testsite < mail@testsite.com >\n";
    $headers .= "Cc: testsite < mail@testsite.com >\n"; 
    $headers .= "X-Sender: testsite < mail@testsite.com >\n";
    $headers .= 'X-Mailer: PHP/' . phpversion();
    $headers .= "X-Priority: 1\n"; // Urgent message!
    $headers .= "Return-Path: mail@testsite.com\n"; // Return path for errors
    $headers .= "MIME-Version: 1.0\r\n";
    $headers .= "Content-Type: text/html; charset=iso-8859-1\n";