Is there a way to determine whether an e-mail reaches its destination?

Question

I have a PHP script that sends out critical e-mails that needs to reach its destination. I know how to check whether the e-mail sent successfully, the only issue is knowing whether it actually got to its recipient.

Any suggestions? If there is no way of knowing, how would you handle this situation?

Answer 1

If you make the email HTML based, you can include images in it which contain URLs with information unique to the recipient. You could structure your application so that these URLs trigger some code to mark that particular email as read before returning the required image data.

To be totally effective, the images would have to form a key part of the email, so that the recipient has to make their email client grab the images. You could also make the plain text part of the email just contain a URL to retrieve the full message, again allowing you to track receipt.

How far you take these ideas depends on why you need to know it's been read and to what extent you want to potentially annoy the recipient with an email they can't cut'n'paste, read easily on mobile device, listen to with a screenreader, etc...