Sure these are lots of logistic issues but in reality a consortium of financial institutions could push some of the big players in email to build in support S/M

Sure these are lots of logistic issues but in reality a consortium of financial institutions could push some of the big players in email to build in support S/MIME which seems similar enough to HTTPS (not that this is the gold standard but a good start). But I do think there is be a big incentive to validate an email sender... Reasons are many and the climate should support it 1. Increased public awareness of privacy threat 2. Institutions build their business on trust 3. Fraud risks are huge, institutions have some skin in that game and some incentive to reduce that threat