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Re: Block IPv6-only at the border

2008-04-16 17:30:51

John C Klensin wrote:

which of the two of you did I hear volunteer to start
writing a coherent and unified "best practices" I-D?

| ideally someone with some of that experience first-hand

Please take this off the list and start writing.

Nothing to do from my POV:
| If an SMTP server has accepted the task of relaying the
| mail and later finds that the destination is incorrect
| or that the mail cannot be delivered for some other
| reason, then it MUST construct an "undeliverable mail"
| notification message and send it to the originator of
| the undeliverable mail (as indicated by the reverse-
| path).
| When the receiver-SMTP accepts a piece of mail (by 
| sending a "250 OK" message in response to DATA), it is
| accepting responsibility for delivering or relaying the
| message.  It must take this responsibility seriously.
| It MUST NOT lose the message for frivolous reasons,
| such as because the host later crashes or because of a
| predictable resource shortage.

If you would mean something else you would have written
something else, and I made sure that this isn't the case.

"My network is IPvX and can't do IPvNOTX" is predictable
under normal circumstances as in Arnt's example => your
SMTP did the right thing when it rejected IPv6-only mail.