[Exim] message in log file

Hi

We are running exim3.22 on solaris 2.8 and I keep getting the
following message in the exim_mainlog file.

2002-01-09 11:13:17 Connection from [216.136.173.226]
temporarily refused: not in reserve list: connected=50 max=100
reserve=50

The connectionfrom IP addresses changes all the time.

Do you have any idea as to what could be causing this. Is
something wrong in my configuration file.

Thanks
Cheers
sherona