You'll need to post more information about your setup. Please post at least what SA told you in your false positive. SA tells you which rule added how much to the score and thereby gives you hints about what's up and what may be changed.
SA is the defacto market leading solution. There may be others, but I don't know them
What you'll find on the web are some solution providers who offer to handle the mail for you, but for most people these services are too costly.