title: Cannot send mail to yahoo (any address) using PHP code and SMTP server
body: <p>I have the following code which sets up the SMTP server:</p>
  
  <pre><code>ini_set("send_from", "test@gmail.com");
  ini_set("SMTP", "smtp.gmail.com");
  </code></pre>
  
  <p>and i create a simple mail in this way:</p>
  
  <pre><code>mail("test@yahoo.com", "A subject", "My message for you", "From: TEST");
  </code></pre>
  
  <p>When I run this code, it fails to send mail to <strong>Yahoo</strong> e.g. <strong>some.email@yahoo.com</strong>. But when i use any <strong>Gmail</strong> mail address as the first argument, it works.</p>
  
  <p>What's wrong ?</p>