DevArticles has posted the last part in their "Sending Email with Ajax" series today - an explaination of the last piece of the puzzle, server-side interaction.

Welcome to the last tutorial of the series "Sending email with AJAX." As you may have guessed regarding the title, this three-part series explains the development of a fairly simple AJAX-driven email client application, which offers some interesting capabilities for sending email, as well as for displaying and adding contacts, all without the need to involve page reloads.

They start off with a quick recap of the previous parts, and move quickly on to the script you'll need to accept the Ajax messages from the client (in this case, PHP). They show you how to have it add a contact to an XML file and send off the message to the server to be handled through PHP's mail() function...