I have a small website and would like to encrypt incoming email using gpg. Is there a way to force sendmail to check email and encrypt it if its not already encrypted?

I'm using GPG on a linux server.

Thanks

[added]Someone asked what I hope to accomplish. My intent is for the users of the email to become more familiar with seeing thier own email encrypted and losing that fear of the unknown. The side benefit is that the email can't be looked at later down the road. If the email isn't encrypted on its way in, I'm unable to do anything about it. I'm assuming most email would be nosed around with once its already on my hard drive, so GPG would protect against those issues.