[exim] Help! SMTP data timeout (message abandoned)

Hello,

I'm getting tons of messages rejected with the following error:

2004-10-25 20:36:38 SMTP data timeout (message abandoned)

The error is coming from a number of sources, including clients
sending messages and incoming messages.

I've searched the list archives and can't come up with any recent
issues that seem to apply and my connectivity is fine otherwise.

Making it more frustrating, I haven't been able to get this error
myself. Any ideas what might be causing this and, more importantly,
how I can fix it?

Tom Wiebe