Re: [ietf-smtp] Make username optional in email addresses

[Valdis Kl ē tnieks <[e-mail]>]

On Fri, 17 Feb 2023 22:40:05 +0000, Paul Smith said:

> In the same way that Web browsers will "autocomplete" a URL of
> "example.com" to "https://www.example.com", a compliant email client could
> "autocomplete" an email address of "example.com" to "[e-mail]"

And how does the client know that it should auto-complete  and it isn't looking
at a local username that happens to have a period in it?  Remember that there's
a lot of silly top-level domains, so you can be looking at a  bare
'george.fish' and not knowing if that's a local user or a domain name. And it's
quite possible that an MUA doesn't actually have a good way to verify that a
localname is in fact valid without actually submitting the mail.

(A quick look at this mail's From: line should convince you that local parts with a
dot in them do in fact exist. :)