[fakedcake]

The biggest roadblock to serverless email is that it doesn't use the http protocol. Afaik all serverless providers only process http(s) requests, usually specifically on port 80/443 only, so SMTP/POP3/IMAP don't simply work serverless. You'd need at least a proxy that wraps them in http, or convince all email services to support a new http based protocol.

Arguably, a http based email protocol would be a good thing. Not only would it enable serverless, it would also enable all the features of http/2&3, like compression, multiplexing and better pipelining. Someone would just need to define it. The downside would be that VPS providers can not limit mail spam from their servers by just blocking outbound traffic on certain ports, so you'd find all their IPs to quickly be blacklisted. So the protocol should ideally somehow also offer some form of spam detection/prevention that works better than simple IP blacklists to prevent that.