title: Throttling outgoing email using PHP code
body: <p>I'm in the midst of coding a throttling code in php for outgoing emails.<br>
  I want to know what algo is good for throttling?
  Can any help to comment on the below design?</p>
  
  <p>Specs:<br>
  The emails are stored in MySQL.<br>
  PHP will retrieve the data and use PHPmail to send.<br></p>
  
  <p>The plan so far:<br>
  Grab the email column from the database. <br>
  Take out the domain, IDs of the records will be paired.<br>
  Check the domain (mx &amp; a records).<br>
  Update the valid domains in a table.<br>
  Sort the domains in stacks of uniques.<br>
  Pop each stack once, using the ID to search for the record and send the mail.<br>
  Goto next stack, repeat from first stack when done.<br></p>
  
  <p>Thanks in advance for any help!
  Jase</p>