Still problems with SpamAssassin. Disk space increased, doesn’t appear to be a resource issue:

Plenty of disk space:

     # df
     Filesystem 1K-blocks Used Available Use% Mounted on
     /dev/vda3 27016320 5755716 19907756 23% /

Plenty of memory:

     # free
     total used free shared buffers cached
     Mem: 4053548 1504976 2548572 6136 46200 595264
     -/+ buffers/cache: 863512 3190036
     Swap: 2097148 0 2097148

Plenty of CPU:

     # uptime
     14:45:14 up 3 min, 2 users, load average: 0.63, 0.62, 0.28

I am back to researching this.  Any suggestions most appreciated.