Given all the issues with PGP mail, SMTP, and IMAP, as well as the flexibility of Matrix, I was wondering if it makes sense to apply Matrix to non-realtime communication like email. Developments like autocrypt and pEp just seem like attempts to fix a broken protocol rather than anything cohesive. Other attempts like Dark Mail don't seem to have yielded much.
I imagine implementing something like this would be pretty straightforward and could either be in the style of a local IMAP/SMTP bridge (similar to Protonmail Bridge) or as an extension of existing email clients. All the matrix magic and encryption could be very transparent, and for users which don't have a matrix account associated with their address, a regular SMTP homeserver bridge could be used to send and receive for out of band users.
Anyone have any ideas, resources, or comments about this?