There is a trend in inboxing-rates: if there is no interaction with a sender, start moving the messages to spam and start penalizing the sending IP address. Thi

There is a trend in inboxing-rates: if there is no interaction with a sender, start moving the messages to spam and start penalizing the sending IP address. This means senders, in order to protect their IP reputation, do well to remove recipients who don't engage with email sends. The two most typical ways to do that are a tracking pixel or tracking if a link is clicked. It seems like a natural progression. What is unfortunate is that the inboxes are really part of the problem because measuring engagement and lowering spam is a good thing, but just because I did not open the mail (load tracking pixel) or click a link, does not mean I did not engage. Reading a subject line is good enough for a lot of email I get. Many users have images blocked, and tracking pixels are rendered useless. I still have email that Gmail puts in spam that I really want, but I only use the subject. It is a non-trivial problem because there is an arms race between inboxes wanting to prevent spam and spammers wanting in, and in the middle is businesses who have legitimate email to send or normal people sending email.