> The score is derived from the combined corpus of our contributors to > ensure minimal false positives of ham being detected as spam - that is, > scoring 5.0 or more. >
I don't feel I've done masscheck justice here. The routine is a lot more complex than this! I should also note that masscheck tries its best to get verified ham email to score as low as possible, for example. Sometimes it's not possible to have good spam detection without a little collateral - you should always need to have multiple rules, or combinations, that tips you over the spam level.
