[Top] [All Lists]

Re: [ietf-smtp] Reducing minimum recipient limit?

2019-12-16 10:03:36
Viktor Dukhovni <ietf-dane(_at_)dukhovni(_dot_)org> wrote:

this an area where practice appears to have diverged from the standard.
I not keen to see the limit reduced, but perhaps advice to clients to
default further below 100 than they may doing already may be warranted.
I can only speak to Postfix, which defaults to sending up to 50 and
accepting 1000.

I would like a requirement that servers must not reject the entire message
if there are up to 100 RCPTs even if the server returns 452 for some of
them. Senders can then pipeline safely.

First, even if such a requirement was acceptable - and I think there are cases,
such as an address list including a honeypot address - that make it
unacceptable - I don't see how it could be effectively imposed at this point.
The best you could do is have an SMTP extension that announces this as a

But a new extension seems like a lot of work, especially since you can always
use BDAT to pipeline safely. So perhaps a better approach would be to make BDAT
"more required", whatever that means.


ietf-smtp mailing list