AKA, "Shadow profiling" - you can prevent it somewhat by sending Gmail users Protonmail or Tuta's password encrypted email.
back
1 comments
which in many cases they just won't open and then complain about it
Not my experience. For example, when I rented a house, I sent some personal documents to the landlord through such password protected email and also texted them the password to their phone. The called me about it and I explained to them this was the latest "secure mail" technology, as "old email" are just like postcard mail which anyone can read. And hence "old email" technology is not secure enough when we are dealing with financial documents, and personal ids etc. I later ended up helping them create a new ProtonMail id which is what he now uses as his primary mail account.