The problem with read receipts is that people have the option to not have one sent. I have domain admin privelages and I could force the option, but I don't want it to be forced. Instead, I am looking for an alternative way of verifying an email has been read (or at least opened).
One possible solution I thought of is a spammer's technique of embedding an image in an email. When the image is loaded they know your email address is legit. Is there something out there that would let me do something similar on a much smaller scale? (about 50 employees). Any ideas?