Re: mail does bounce (was: Customers down?)

[sthaug]

> > I know for certain that Postfix and Smail will immediately bounce a
> > message when the domain is authoritatively non-existant.  I'd be very
> > surprised and dismayed if sendmail and all other true SMTP mailers did
> > not do exactly the same thing.
> 
> Sendmail most definitely does not, instead treating the error as a 
> transient error, issuing an SMTP error code in the 400 series, and
> continuing to try to send the mail for up to five days (the default),
> or whatever the mail server admin configured for that particular
> server.
> 
> I think I like it better that way. Just because both nameservers are
> temporarily down doesn't mean the domain doesn't exist. :P

Seems to me you're talking past one another. If all nameservers for a
domain are down there *is* no nameserver which can say that the domain
is authoritatively non-existent. (OK, you could get a negative caching
answer from one of the authoritative servers on the level above, but
that's a different issue...)

I agree with Greg Woods - if a domain is authoritatively non-existent,
I'd expect a sane mailer to bounce the message.

Steinar Haug, Nethelp consulting, sthaug@nethelp.no