Le 06/01/2011 21:01, IT geek 31 a écrit : > [snip] > > Outlook is all-or-nothing - it can force encryption for all > recipients, regardless if they have a certificate or not, or none at > all. > AFAIK, it has no way of determining if a recipient has a certificate > and if so forcing encryption. > > Regardless, I'm after a Postfix solution as that would educate (for > want of a better word) all senders, regardless of client.
First, let's make sure we agree on the basics. there is no way to prevent a client from sending unencrypted data. the server can reject, bark, ..., but only after seeing unencrypted data. second, even if the server could stop the client before it talks, the client could be talking to someone else. (example: dns issue...) so I guess what you want here is to teach your peer but not to guarantee that he won't be sending sensitive information to the wrong destination or without encryption. if so, you might reject based on content-type (http://tools.ietf.org/html/rfc1847#section-2.2). if you do so, think about general mime structure (not just a sample mail).
