In WHM goto install perl module. Install the modules
Digest::SHA1
and
Mail::SpamAssassin::NoMailAudit
Now reinstall spamd. I would suggest using this
http://www.cpanelappz.com/exiscan+clam+exi...m-installer.htm . It is a clamscanner (antivirus) and spam protection.
Then restart everything:
service exim restart
I was having trouble using the latest edge but the above fixed it. See if the above works for you