How can I check if an e-mail has been read using POP3/SMTP?

Question

How can I check if an e-mail has been read using POP3/SMTP?

I am able to read e-mails, but I can not figure out if the e-mail has been read or not. Any suggestions are appreciated.

Answer 1

There is no completely reliable way to do this, while some servers support Read receipts it is dependent on the client to respond to the receipt request.

Another way people do this is by embedding a tracking image into an HTML email that will get pulled from a server and that hit constitutes the read however this is often not accurate as most email reader block html external content by default.

Answer 2

With POP3, emails are almost always deleted from the server after they are read. When a client connects to a POP3 server, the server usually transfers emails to the client and then deletes the email from its own storage. So, if you can read an email, chances are that it hasn't been read.

Answer 3

As far as I know this is a client side only detail when it comes to POP3. If you wanted to have the status reflected on multiple clients you'd need to used IMAP. With web mail readers they keep track of the unique message ID and whether or not it has been read on the client, but if you were to load it on a desktop pop3 client, it would not be flagged as read.

Answer 4

Sign up for a free account on statcounter.com. Goto the install code options, choose invisible tracking button and HTML only counter. Statcounter will now provide you an HTML Image snippet that you have to insert inside the body of your HTML email message.

The image isn't visible in the email but the person will have to click "Display Images" when they open their email client.

This is about the only way you can do it if your server or client does not support read receipts.