Question

Possible Duplicate:
PHP: Check who had read sent email?

I’m writing a tool in PHP that will be sending notifications to members using mail(). Is there a way to get a notification when an email has been opened by recipient? Granted some systems do not support that but for those that do, how can I do that?

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UPDATE:

Tested different ways. The best seem to have 1×1 image included. Avoid including logos and other images. They look quite ugly when blocked. 1×1 seem to have too small of an area to show security warning when blocked.

Answer 1

The request is made in the email by adding an optional header to the message, like this:
Disposition-Notification-To: sendReceiptToAddress

Just add something like this as one of the headers for the mail message:
$headers .= “Disposition-Notification-To:\r\n”;

Also, if this is an HTML formatted email (and you have a web server to handle the requests), you could add a request to a PHP script that will return a 1×1 transparent tracking pixel to the email body itself, with a URL like:
http://mydomain.com/emailtracker/track.php?message=MyMsgId&user=MyUserId

This isn’t 100% either, since people usually have the option not to download images for an email.