[exim] Most likely reason for Spam ACL "cannot parse spamd o…

Checking with "exim -d-all -bh IP_ADDRESS <filename":

>>> processing "warn"
>>> check spam = nobody:true/defer_ok
>>> trying server xx.xxx.xxx.xxx, port 783
LOG: IIJ8IW-00040C-PP spam acl condition: cannot parse spamd output
>>> warn: condition test failed

What are the most likely reasons for this Spam ACL

    "cannot parse spamd output"  ?

How to test?

SpamD is running and answering other requests (e.g., SpamC)
for checking.

All local addresses are permitted to SpamD. This doesn't
look like a "total" failure anyway (permissions, permitted
IP, wrong spamd address or port, etc.)

Environment: Cygwin, Win2003, Exim 3.51
--
Herb Martin