North American Network Operators Group
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Re: Weird DNS issues for domains

  • From: Peter
  • Date: Fri Sep 30 03:43:08 2005
  • Newsgroups: newsgate.nanog
Crist Clark <[email protected]> wrote:
[...]
> The problem I've seen is when an SMTP server does not accept emails
> which have non-resolvable MAIL FROM domain. When the sender is a
> dumb SMTP client, not an MTA, this can cause problems.

Well, that "dumb SMTP client" should stop pretending to be a MTA then.
If it can't queue and retry, it shouldn't even *think* about looking
for MX records.

Besides, what sort of "dumb SMTP client" did you have in mind?
Formmail scripts? Worms? Outlook Express? I can't say I'd miss mail
from any of those.

> (I noticed this happen to a high traffic customer who had both of
> their DNS servers in the same /24 located in Slidell, LA. Needless
> to say, they were down for more than a few hours when Katrina rolled
> through.)

Having reachable DNS isn't going to help anyway if the MX host is also
unreachable for an extended period. Mail is still going to bounce
after a few days if somebody doesn't fiddle with DNS.

-- 
'Twas a woman who drove me to drink, and I never had the courtesy to thank her
for it.
								- W.C. Fields