I literally bought it into, both as a customer and investor. :-)
And did you update your email signature in the way the OP suggested? Specifically, do you let everyone getting email from you know that you not only track that read it, but when they read it, and even where they were when reading it?
I ask, because that would be the ethical way to handle what this app is doing for you.
I don’t need to be told that an electronic communication may be tracked because I was born after 1980. Why do you?
You should have disclosed that you were an investor in the first comment you made.
Literally, every glowing review I have seen comes from a related party, whether it is an investor, employee, or friend of the CEO.