On Sun, Jan 02, 2000 at 12:31:00PM -0800, Owen DeLong wrote:

...

Attempting to resolve a.b.c.d.e.f.g.h.i

If you get back a return value from DNS that says "Authoritative answer, a.b.c.d.e.f.g.h.i does not exist" Bounce the mail.

If you get back a return that says "Resolving a.b.c.d.e.f.g.h.i timed out without a return" Queue the mail.

This also works for i, h.i, g.h.i, f.g.h.i, etc.

I agree that this is the most sensible minimum functionality. What do you break if you treat what you consider persistent terminal conditions as transient?

Usually, if I send something to foo@delnog.org instead of foo@delong.org, I get a bounce back before I depart my MUA. You would break that.

Perhaps your business policy is to deliver all mail that can possibly be delivered, making the assumption that everything's transient unless the system has what it considers reasonable proof that it is indeed permanent (after for instance several attempts spread out over a period of time).

I think that an authoritative nameserver saying "I know for certain that domain xyz doesn't exist." is reasonable proof that an error requiring intervention exists.

Personally, I don't like systems which do not have backup paths to deal with transient conditions. And we do know that even "authoritative does not exist" can be a transient error condition caused by a registry glitch etc. Sure, we can all just ignore reality and assume we live in a perfect world, but....

But a registry glitch is an error requiring intervention, therefore, I would much rather receive my mail back immediately so that I can intervene, than have it sit there while everything else breaks hoping that it will eventually clear itself. Owen

Cheers, Chris

-- Christian Kuhtz Architecture, BellSouth.net <ck@arch.bellsouth.net> -wk, <ck@gnu.org> -hm Atlanta, GA "Speaking for myself only."