Amavis 100%

[Curtis NPC]

Now I've noticed that amavis is taking up 100% of the CPU. In fact just 
a few minutes ago I had several amavis processes running at the same 
time, all sucking up resources.
I had to stop all mail related services. Kill -9 on all amavis 
processes and then restart them all. Things were calm for a while, but 
now....

Any ideas why this happening.

Here's what I get on the process:

11082 ?        Ss     0:00 /usr/sbin/amavisd-new (master)
11101 ?        R     10:26 /usr/sbin/amavisd-new (ch7-11101-07-9)
11529 ?        S      0:00 smtp -n smtp-amavis -t unix -u -c -o 
smtp_data_done_timeout=1200 -o smtp_send_xforward_command=yes -o 
disable_dns_lookups=yes -o max_use=20
11566 ?        S      0:04 /usr/sbin/amavisd-new (ch13-avail)
11697 ?        S      0:00 smtp -n smtp-amavis -t unix -u -c -o 
smtp_data_done_timeout=1200 -o smtp_send_xforward_command=yes -o 
disable_dns_lookups=yes -o max_use=20

Top shows thtat is is process 11101 that's taking up all the CPU

11101 amavis    20   0  269800 142780   7912 R 100.0  1.8   7:30.26 
/usr/sbin/amavi