All that's really needed is for internet communcations to be afforded the same privacy protection as other forms of communication.
In the good ol' days, the number that I phoned may have been fair game, but any conversation I held once the connection was made was considered to be private. Even if I asked the person at the other end of the line to pass the information on to other people.
In the good ol' days, the address on the envelope may have been fair game, but the content of the envelope was considered to be private. Even if the envelope contained a message and an instruction to send a copy of the message (in a similarly sealed envelope of course) to each of my friends.
So the principle appears to have been: any information that is needed by the communication service provider in order to correctly connect or route the communication is fair game, but the information thus communicated is private. Even if it contained further communication instructions for other service providers such as mail distribution services.
Unfortunately it seems to have become the unchallenged norm that internet communications are not subject to the same privacy principles. If they were, then the only "fair game" part of the protocol would be the TCP/IP headers - IP addresses, port numbers, etc. The contents of the frames (be it IMAP, SMTP, HTTP or whatever) is part of the information content of the communication and (under the good ol' principles) should be considered private. It is not (or at least should not) be used by the communication provider in order to connect or route the communication.
So we don't really need any new definitions of privacy and whatever. All we really need is that the law observes the old principles correctly.
One of the interesting effects of universal encryption of communication is that it enforces the same level of privacy that's applied to other forms of communication. We need to point out to law enforcements and lawmakers that the use of encryption does not conceal anything that would not have been concealed in traditional communication.