On Mon, 29 Mar 1999 16:58:37 EST, Greg A. Woods wrote:
> Wait a minute here Mark et al. That's a load of rubbish. If the DNS
> doesn't work then SMTP won't work either (at least not on the public
> Internet). You *MUST* have a valid MX (or A) RR in the DNS in order for
> an MTA to find your host and connect to the SMTP port.
Hi Greg,
The DNS resolvers queried by the _remote_ host for MX lookups are seldom
the same resolvers used by the _local_ host for name resolution.
What the guys are saying is that it's usually unreasonable to reject
mail in a situation where the _local_ host's resolver is cooked.
> If not having DNS is a frequent problem then you've probably got a
> configuration error in your DNS, just as you discovered.
Well, what you're proposing allows me to cause all your mail to bounce
by trashing your resolver. Since your resolver is often (by necessity)
more publically accessible than your MX might be, that's risky.
But that's not the point. The point is that it's rude to bounce mail
just because your DNS is trashed, so most people are careful not to do
it. If you're happy with breaking this general rule of thumb, go ahead.
Just be careful about the unqualified advice you give to others.
Ciao,
Sheldon.
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