John C Klensin wrote:
Question: Is it time to formally deprecate 821 and, in particular, the main feature that distinguishes it: the use of HELO by SMTP clients? We would still need to require that SMTP servers accept it, but we would tell full-capability clients (including the client side of relays and gateways) that HELO is obsolete. One corollary of this is that we'd be telling low-capability clients, particularly those that are part of MUA systems, that they should be talking to Submit ports, not SMTP ones.
Yes, it is time! What is obsolete is obsolete, and should be tagged as such. For example, I wouldn't want to buy, say, an "SMTP-enabled camera" that is not actually capable to send photos in a reliable way.
As for servers, I'd recommend that they must limit acceptance of the obsolete protocol to a configurable set of addresses which, in their default configurations, should either be empty or just include 127.0.0.1.
Thanks for continuing your effort, I'm looking forward for the I-D Ale
