SMTP doesn’t really have a universally agreed way of handling authentication, error handling nor even encryption. There are several standards floating about, many of which are little more than pseudo-standards.
> What would you suggest to replace e-mail while retaining its flexibility?
There’s no reason why we cannot redesign the email paradigm around a totally new protocol. The problem isn’t that’s it’s technically difficult, it’s that SMTP is too prevalent now. It would take someone like Google abusing their market share so bring in a successor.
Also any replacement would need to be at a protocol level. A lot of the attempts I’ve seen have also tried to modernise the experience as well (like Google Wave) but the reason email is successful is because it is familiar.
As far as I can see, jmap only provides means to upload email to your email provider, it doesn't actually tell how that email ends up from one email provider to another, which is what SMTP does.
Granted it's already nicer for clients not to need to configure SMTP to begin with.
Yes, one confusing aspect of SMTP is that there is a server-server part (listening on port 25) and a client-server part (465 or so, usually authenticated). I haven't dug in-depth, so maybe they are exactly the same protocol though.
Acessing port 25 of server is usually blocked by ISPs as a way to prevent spam.
The difference in ports is due to SSL/TLS expected to be automatically applied on 465 iirc like 80/443 for HTTP(S) (you can also encrypt 25 by issuing STARTTLS after setting up a connection but it's not the default and might fail I think).
Authentication with mail is separate, usually to allow for relaying whilst anyone can usually drop emails IFF your server is the destination.
Confusing and needlessly complex? Yep. Natural result as of uncontrolled evolution? Yep.
One of the big mistakes with the design of IMAP was that there wasn't a standard Out-Box where a client could rely on the IMAP server for sending the email. I'd have loved to see a world where mail clients only had to implement IMAP and nothing else.
> What would you suggest to replace e-mail while retaining its flexibility?
There’s no reason why we cannot redesign the email paradigm around a totally new protocol. The problem isn’t that’s it’s technically difficult, it’s that SMTP is too prevalent now. It would take someone like Google abusing their market share so bring in a successor.
Also any replacement would need to be at a protocol level. A lot of the attempts I’ve seen have also tried to modernise the experience as well (like Google Wave) but the reason email is successful is because it is familiar.