First I would like to thank the Contribs community for a great product.  I have no experience with Linux and managed to set up an email server, complete with the Spam filter and Antivirus.  It took a little digging, but I found almost all my answers in the documentation or the forums.
I do have one question concerning SpamAssassin.  I have 3 directories accumulating Ham, Spam and missed spam.  I'd like to train the Bayesian filter to improve its accuracy, but I am unsure about which mail to have SpamAssassin learn.  The Ham and Spam folders contain mail that SpamAssassin has already filtered correctly.  Is it useful to run sa-learn on correctly filtered email or should I just run sa-learn on the missed spam?
thanks,
Pete