Hi, John.

>Do you have no concerns re confidentiality if you are sending message text to somebody else for heuristics?

No, Cloudmark is quite serious. They have a privacy policy and they are audited, but also, the messages you block (report as Spam to SpamNet) are the ones that you don't care. 8-)

The product won many prizes. Take a look at the site and it will give you an idea. In this times, you can't trust almost anyone, but they look solid enough.

See you,