A modern, standardized API would negate vendor lock in. And it wouldn't have to replace SMTP, it could simply be an alternative option. There is no reason that

A modern, standardized API would negate vendor lock in. And it wouldn't have to replace SMTP, it could simply be an alternative option. There is no reason that sending an email can't be done with a simple, single API call. The back and forth "dance" that SMTP requires is just an absurd waste of time. There may have been a good reason for it at some point but today, it's hard to imagine what that was.