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Re: What does this message mean?
On Fri, Dec 01, 2000 at 07:36:54PM +0100, Ralf Baechle wrote:
> Since the recent zmailer upgrade I had several bounces like:
> Original Recipient:
> Control data:
> smtp frob.de firstname.lastname@example.org 99
> Diagnostic texts:
> smtp; 500 (DNS: MX host does not support SMTP: bar.de)
> What is causing a ``MX host does not support SMPT:'' error?
> I was speculating it might be related to WKS records without SMTP but none
> of the MX hosts has a WKS record at all.
It depends ... I used to get those too, not anymore.
(And no, it isn't WKS related. See man-page of 'smtp' about WKS.)
Over past 3-4 weeks I have had these bounces only when
- somebody is just changeing DNS zone datasets, and/or
- MX defined target system does not have A-record
(They are very rare now. 0-1 per week.)
The system is somewhat sloppy here, it uses getaddrinfo(), which
like gethostbyname() resolves text representation of addresses
and CNAME redirection of DNS lookups.
The DNS specification says that the MX value must be hostname, and it
must have an address, specifically CNAME is not valid target for MX.
If you have a system with its local getaddrinfo(), do try to check
if it *really* works, or does it fail wrong way in case of timeouts
on the lookups ? (Linux glibc 2.1 fails ... 2.2 is propably ok,
not sure of other versions.)
cd transports/smtp; make;
That should give "temporary failure in name resolution",
glibc 2.1 gives ... Odd, now I can't check that, where
are my glibc 2.1 machines ... hmm...
Anyway, it was something else than "temporary" error.
For that reason the configuration system has option:
/Matti Aarnio <email@example.com>