title: [PHP Warning: mail(): " sendmail_from" not set in php.ini or custom "From:" header missing
body: <p>I am trying to use PHP's mail() function to send a test mail.</p>
  
  <pre><code>$to = "****@gourab.me";
  $sub = "Php Mail";
  $msg = "Test Message From PHP";
  
  mail($to, $sub, $msg, "From: **********@gmail.com");
  </code></pre>
  
  <p>When I try to debug it through <code>step</code> in <code>phpdbg</code>, it shows the message:</p>
  
  <pre><code>[PHP Warning: mail(): " sendmail_from" not set in php.ini or custom "From:" header 
  missing in C:/xampp/htdocs/tinyProj/mail.php on line 4]
  </code></pre>
  
  <p>I cannot understand why?</p>