Using such techniques would probably reduce the chances that I would respond. I would suspect it would increase the possibility of the email being blocked as spam as well.

I would consider this as pretty rude and as a strong red flag about you.

Well, it makes clear what to expect of this person as a PhD student and makes it easy to come to a decision. Having a patronising boss is already unpleasant, but having a patronising student really takes the biscuit. Unsolicited emails are just that: unsolicited, and, while it would be nice if they would be answered, random people cannot expect that profs with 300 mails a day can respond to everything they receive.

You would do better to spend your time carefully customising the messages.

Using tracking software for any email to anyone is rude.

This is how (beginning) Ph.D. students feel about writing to their own advisers, now how do you think professors feel about random students doing what you just said?

My advisor doesn't reply to about half the emails I send him. Some of them he reads and tells me later that "he saw the email"; others get lost in the 100-or-so new daily items in his inbox. I don't know if you sent him one of the emails, but it could give you a good idea as to why you didn't get a reply from someone who is busy, and might not even answer his students or colleagues.

keep in mind that any good email client won't bite the bait.

Related, although in the opposite way (server unwantedly adds read-receipt) Is it rude to request a read receipt when emailing the professor?

AFAIK, my email client blocks all the html content of incoming mail, so the technique you describe will not give any reliable information. I don't think that I am unique in that situation.

IDK, what exactly is meant here, but are you talking about tracking the image usage ? Your description sounds like hacking, but it's unlikely that you mean that. I guess this is also why so many angry comments are here.

@CoderInNetwork: Many people in academia use dedicated webmail servers, where the emails are text-based. Embedding images won't work.

Surely it only takes one person with a bit of free time to take offence for this to land you in hot water with your current university?

@CoderInNetwork This assumes the client emailer does the http request to the server for the image. And if it doesn't (as does mine), you don't get anything.

Dating websites have a feature which allows you to see if your potential love interest has read your message. Unfortunately all it does is sink the users' moral as they realize their messages are not lost in oblivion, but rather that they are themselves not attractive enough. Long story short, don't be that guy on the dating website...

A well composed email should include a link to your website where you show off your work. If you are really curious about who took interest in your email, check your website analytics and make guesses about who the visitors might be. What you should not do is include a unique tracking ID in that link. The primary purpose of including the link should not be tracking at all—it should be to show off the good work you have done.

If we were talking about postal mail, one could include a check. Then all you have to do is check if the prof cashed the check. Surely, the technology must exist to attach money to an email.

@CaptainEmacs He doesn't expect an answer. I don't know where you got it from, that he's expecting an answer. He wants to know if the email has been read or not. If it hasn't been read, he can resend the email. If it has been read, it means that his cv was just not interesting enough to worth a response, and that's fine.

@Andrei Indeed, perhaps my assumption that he wants a response is too strong - but I would think that if he puts a read notification in the email, he is like the boss I once had, he is looking over my shoulder while I am working; unpleasant, even if he does not say anything or demand anything.