Email security & content filtering

摘要

Email security is a bit of an ambiguous term. It can refer to keeping outbound messages secure from unauthorized prying eyes. It can refer to ensuring that incoming email from trusted sources is secure. It can mean that incoming email does not pose a threat to the enterprise, and I'm sure that there are other things that might fit neatly into the category. Fortunately, we don't need to be quite that rigorous in defining the details of the problem.