[exim] SMTP connection time out error

Greetings all, I have a persistant problem receiving mail from one of our
clients. I can send to them just fine but receiving has never worked.

I keep seeing the following message in our log files:
SMTP command timeout on connection from sub.<domainname>.com [x.x.x.82]

Ive disabled our dns rbl filter, added them explicitly to
/etc/hosts.allow, and even upp'd our SMTP timeout setting from the default
5min to 20min and nothing seems to help.

Searched around for them being listed on a DNS RBL but they are not.

I'm not sure if this is something that exists on the distant end mail
server causing this or if it is my mail server.

Using Exim 3.35 on Debian box.

I know, I know, should be using 4.x but I haven't found yet a very good
doc on how to upgrade to 4.x easily and this is a production box.

Any help is GREATLY appreciated.



TIA,


Bryan