In article <FC831208-97A3-4F1B-A37C-F8646C3FB208(_at_)gmail(_dot_)com> you
write:
SMTP servers could be key servers without having the private key of
individuals?
Sure. If they double as HTTPS servers.
As others have noted, this topic has come up more than a few times before.
Here's a recent draft we wrote for a simple per domain https key
server, based almost entirely on existing standards. It distributes
public keys. Managing your private keys on all of your MUAs remains
as intractable a problem as it's always been.
https://datatracker.ietf.org/doc/draft-bhjl-x509-srv/
R's,
John