[Exim] DNS "query failed" and "timeout" messages

Greetings,

The company I work for has recently had the Exim e-mail server installed for
the use of this office, and it's working very well.

I have one question- I'm hoping someone can answer it- I need very much and
as soon as possible to allay the fears that something's wrong with our Exim
server.

We have Exim installed in Mac OSX. In the console logs, we're getting
messages indicating DNS server "timeouts" and "query failed," but we're
seeing this on a constant basis. What worries us is that we're confident
that the actual DNS servers are working properly. These DNS servers
(198.6.1.2, 198.6.1.3, 198.6.1.4, 198.6.1.5) are external to our network and
they are run by a huge company called MCI/WorldCom/UUNET.

Let's say there's an e-mail on the queue whose host can't be resolved by the
DNS servers. Would such an e-mail remain on the queue, so that Exim
continues again and again for days on end with all DNS servers available, to
try to resolve the e-mail's domain name?

If I was told that one e-mail with an un-resolvable domain name could
produce many many many DNS "query failed" and "timeout" messages in the Exim
logs, then I'd feel more comfortable. At the moment though, seeing all
those "query failed" and "timeout" messages, it feels like there's something
very wrong with something.

Can you please help me interpret these logs and let me know if they seem to
indicate a serious problem, and what I should do to troubleshoot or fix it?

Thank you very much for your help, I appreciate it. I hope it's good news
that you have to share!

Philippe Pakter
phil@???

from the console log...

Mac OS X Version 10.1.1 (Build 5M28)
Feb 13 10:17:40 localhost last message repeated 7 times

Feb 13 10:21:40 localhost lookupd[201]: Caught SIGHUP - reset

Feb 13 10:22:09 localhost lookupd[201]: DNSAgent: dns_send_query_server -
timeout for 198.6.1.4

Feb 13 10:22:17 localhost last message repeated 3 times

Feb 13 10:22:17 localhost lookupd[201]: DNSAgent: dns_fqdn_query_server -
query failed for 198.6.1.4

Feb 13 10:22:33 localhost lookupd[201]: DNSAgent: dns_send_query_server -
timeout for 198.6.1.5

Feb 13 10:22:35 localhost lookupd[201]: DNSAgent: dns_send_query_server -
timeout for 198.6.1.5

Feb 13 10:22:38 localhost lookupd[201]: DNSAgent: dns_send_query_server -
timeout for 198.6.1.4

Feb 13 10:22:50 localhost last message repeated 2 times

Feb 13 10:22:53 localhost lookupd[201]: DNSAgent: dns_send_query_server -
timeout for 198.6.1.5

Feb 13 10:22:57 localhost last message repeated 2 times

Feb 13 10:22:57 localhost lookupd[201]: DNSAgent: dns_fqdn_query_server -
query failed for 198.6.1.5

Feb 13 10:23:11 localhost lookupd[201]: DNSAgent: dns_send_query_server -
timeout for 198.6.1.4

etc. etc. etc.

Is this normal or the sign of a problem?