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Re: No A, no MX... but still retrying.


> Date sent:      Tue, 22 Feb 2000 15:24:21 +0200
> From:           Matti Aarnio <mea@nic.funet.fi>
> Subject:        Re: No A, no MX... but still retrying.

> > But THIS case (no A, no MX) seems to be more definite. If we have no 
> > any DNS reply at all - yes, we have to retry. But as soon as we have 
> > NO_DATA reply, we may stop immediately. The address is definitely 
> > wrong.
>     Unfortunately we get NO_DATA for wrong reasons too,

Surely. But IMHO this error is not  much more possible than other DNS 
problems. So, we do not loose reliabulity... at least, lot of 
reliabulity :-). One of my REAL problems is false smtp-policy 
rejections for my direct clients at RCPT TO: stage because of 
temporary complete DNS unavailability. Happily, most of this Zmailer 
host senders use UUCP now.

> that is why
>     the current code behaves like it does.
>     The code, by the way, reads:
> #if 0
>           if (r != EX_TEMPFAIL)
>             r = EX_NOHOST; /* Can do instant reject */
> #else
>           r = EX_TEMPFAIL;
> #endif

Yes. I changed it just 1 hour ago. After that I (and my client)
have got the desired failure report for two hanging messages to 
@email.ru. Just an existing domain with neither MX nor A RR.

So, being testing now. Reports will be published within several weeks 
of statistics.

I believe, this behavior must be configurable (i.e., by 
sceduler commandline). This  choice (silent hanging or false 
rejecting risk?) is really difficult, and may be different for 
different sites.

As to delay notification... yes, it is great feature. But... 
missing feature is not a bug.