[exim] Delay in SMTP "no IP address found for host"

Hi,

I have just set up a mail relay for authenticated users using Debian/GNU
Linux. It seems to work, except that there is about 30 second delay
after submission of mail (from firefox) during which nothing is logged.
After this delay, the following is logged:


2006-07-17 18:16:32 no IP address found for host
my.router.hostname.from.which.mail.is.submitted.com (during SMTP
connection from [xxx.xxx.xxx.xxx])

Why is this? Are there some lookups being done for 30 seconds, then
timing out? How do I disable this, whatever it is. 30 second delay is
too much.

Best,

Mordur