The problem is that only the body is encrypted. Who you are communicating with (and in term, who they are communicating with) is at least as sensitive as what you are writing.
But that's a different problem though, it exists outside of email. The meaning of "who you are" changes depending on how high/low you're on the OSI stack: sometimes it's 00:C0:C1:A4:C8:29 or 60.56.228.48 and sometimes it's anon2342foobar@yahoo.com
If they're wiretapping everything, there's no way for you to hide the fact of a communication taking place, but at least you can protect the data itself using client-side encryption.
> If they're wiretapping everything, there's no way for you to hide the fact of a communication taking place, but at least you can protect the data itself using client-side encryption
No, you misunderstand. With S/MIME, the email headers are not encrypted. This means someone can go to your email provider, get all your emails, and even though these are all S/MIME encrypted, build a nice graph of who you are communicating with, how often, correlate with significant dates, see the subject of each letter, file names of attached files, etc.
Here's an idea: public mail pools. The entire email message is encrypted and randomly routed to one of many addresses. Each customer downloads all the messages from all the addresses in the pool. You try to decrypt each message, and the ones that decrypt are (obviously) yours. The rest belong to someone else.
To make life tougher on spies, add fake email messages to the pool regularly.
