Well, technically there is no way to send an “encrypted email” between to different domains and accounts unless that sort of end to end encryption was setup prior, and you would know that since it’s a PIA to setup. Some institutions WILL send a link to a sort of ‘secure’ WEBMAIL type of environment for mostly single use transmission.
I still have number lists from banks in Germany and Switzerland and Singapore that are single use, which is always my fall back in the event that something happens to authentication. All the lists were verified with 5FA when sent and received, so they are considered uncomprimised at this point.
I recall over two decades ago at least that I had an RSA dongle for my eTrade account, maybe one other company as well. Frankly with the ease of implimentation and availability of Authenticator devices and apps on cell phones I don’t know why more institutions don’t put this in place for users who WANT it, understanding that probably the majority won’t want the initial hassle to setup. That’s fine, but it’s quite easy to integrate and incorporate into a modem operating environment.
I will say, the ONLY reason I have kept my eTrade account (probably less than 5% of trades and value) at this point is access to international markets with currency exchange and access.. how else can one really buy NINTENDO