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. Frank
