Where can I find one of those things that let you know when someone has read the email you sent them?

Question

You attach them somehow to the email, and when that person has read the email, it lets you know by emailing you back. Where can I find one of those? Some cost money so where can I find a free one? Thanks to anyone who helps! :)

Answer 1

Here's a free download for an HTML emali receipt http://www.sentthere.com/download.html