[Sysadmins] DNS....

David Malone dwmalone at maths.tcd.ie
Wed Jan 6 23:24:26 GMT 2010


On Wed, Jan 06, 2010 at 03:13:01PM +0000, James Raftery wrote:
> DNS knows the difference between "DNS servers not reachable" and "name
> doesn't exist".  Only the most retarded email software would treat a
> temporary DNS error as a permanent delivery failure.  Any sender who
> would run software that does that deserves what they get.

I've seen a combination of fetchmail and sendmail do (almost) this.
A recursive DNS was unavailable after a power outage and somehow
sendmail took this as no domains existing. Fetchmail then took the
perminant errors from sendmail (5.1.8 errors) saying that the sender
domain didn't exist as an indication that the mail was spam and
dropped it without logging.

> Hosting everything behind a DSL line is still a pretty silly idea but
> not for that reason :)

I have a few servers at the end of DSL line and it works reasonably
well, though I do have DNS secondaries off-site.

	David.



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