The solutions are already there... there is a lack of will from the corporations to implement them. google checking gpg signature? nope.

The internet is unfortunately not user-centric enough, there is much more value in sending crap html emails "only 10 hours left 50% discount" and scanning your emails than there is to provide users with secure communications.

let's all sign our emails to raise awareness of google's & outlook shortcoming

P.S : we tend not to sign our emails since it is not the standard, standard is de-facto dictated by google and outlook now.

P.P.S : seeing an unsigned email would raise suspicion if the standard was the opposite, a filter could even classify between signed and unsigned

P.P.P.S : you would only bother to verify the identity for the emails you care for

P.P.P.P.S : if you think google does not dictate the standards, feel free to point to me the part of the rfc that mention that residential ips are not valid.