title: Make PHP send an email with an inline image attachment
body: <p>WITHOUT using PHPMailer, Swiftmailer, PEAR, Zend_mail, or any other libraries at all, I want to send an email with an image attachment inline.</p>
  
  <p>The important part here is attaching it inline: I already am able to do everything else.</p>
  
  <p>Inline meaning that it is able to be used by the HTML in the email in an image tag. </p>
  
  <p>I really don't want to use PHPMailer or anything like that--I am not the only one who has tried to figure out how to do this on stackoverflow, and so far all the questions I've seen get nothing but arguments about why they should be using PEAR or Zend_mail or something. I don't want to do that, and I don't want to argue about it.</p>