[TriLUG] Training Spamassassin

[Brian Henning]

Hi Guys,
   As I'm sure the postmasters among us are well-aware, in order to keep 
my Bayesian filter working efficiently, it's occasionally necessary to 
retrain it for new tacks the spammers have invented.   My question is 
thus: Is it "safe" and/or wise to train with only -spam input?  Our 
non-spam profile hasn't changed much, so the previous -ham training 
ought to still be valid...right?  Or do I need to somehow balance the 
training "sessions" with equal parts -spam and -ham even though the -ham 
still looks about the same?

Thanks as always,
~Brian