[Exim] Exim dog slow

Hi there,

I've searched in the archives for this problem, and I found a few
messages about slowness, but nothing related to my problem.

I have setup exim in a basic configuration, as it's not a busy server
(maybe 1 message a minute). No DNS host lookups, no reverse mapping, etc...

I also have about 100 or so relay servers listed in my configuration.
This list grows as we add more servers that need email support.

When I try to send an email, it hangs for about 30 seconds or so.
The first message I get when it finally stops waiting is:

ident callback failed

What does this mean, and why would it cause exim to hang for so long?

Thanks,
James