Sendmail Resolver Issue?
BrianGlacain
I would be grateful for some help. I have installed Slackware 10.1, but
every email I try to send using sendmail hangs in the queue - if I use
the mailq command it shows a message like:
Deferred: Name Server: Yahoo.com.: host name lookup failure
I understand that this points to an error in the resolver system, but
it works OK in any other application, eg I can use links or nslookup
with the domain name and it's fine. Any ideas?
Thanks,
Brian
Robert Harker
but since a Linux specific API has not been published for
nsswitch.conf, sendmail does not use it. Sendmail uses its own
/etc/mail/service.switch file or its built-in defaults instead.
Probably not a problem in this case since you want to use DNS.
The DNS problem may not be with the domain names in the addresses, but
may be with resolving the local host names and addresses. Check that
you have an entry in the hosts file for the local hostname with the
local IP address and that the fully qualified hostname is the first
name listed:
1.2.3.4 thishost.your.dom thishost
My next suggestion is to find which DNS query is timing out.
Run mailq to fine a queue ID of a message sitting in the queue.
Use that queue ID to process the message with sendmail's
DNS query debugging flag (-d8.8) turned on:
sendmail -qIjASAABvu011172 -v -d8.8
In the output you will see a series of "dns_getcanonname" messages.
Look for the one that times out.
BTW, if it the timeout is for a quad A record (AAAA):
dns_getcanonname: trying some.dom. (AAAA)
Then you are probably having a (known) problem querying a Micro$oft
DNS server. If this is the case, add WorkAroundBrokenAAAA
(without a + or -) to your ResolverOptions option:
define(`confBIND_OPTS',`ResolverOptions')
This should fix the Micro$oft DNS server problem.
Hope this helps
RLH
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