To start with I definitely shouldn't be able to sue them or bring legal action against them. That would violate their Right to Communicate. If I put a clause in my EULA that said, "you can't post any information that I can't read," I don't have a right to legally enforce that clause.

However, as a forum owner, I have the Right to Filter the content and users on my forum, so I can ban them. And they're free to go to another forum and communicate that way.

Now, let's say that my forum is ridiculously popular, and completely entrenched, and that I take active steps to kill or buy any competing forums, and eventually my forum becomes the only way to share content online. I still have the Right to Filter, but you could argue (and I personally would argue) that my existence as a monopoly is incompatible with the Right to Communicate. Essentially, I have privatized a public resource, and my forum should either be broken up or (if that's not possible) regulated like a publicly owned resource rather than as a private one.

That last point is where ISPs become interesting. ISPs aren't nationwide monopolies, but they are often regional monopolies. If your only choice of provider is Comcast, and Comcast doesn't follow Net Neutrality, then I would argue that Comcast's existence is incompatible with the Right to Communicate. You don't have a choice of going somewhere else -- if Comcast filters, you just flat-out can't access public content.

It is very, very difficult to break apart ISP monopolies. Additionally, ISP monopolies consume large amounts of public funding and subsidies, which means the public can make a strong claim that they are borderline essential, public utilities, at least partially funded through public taxes and city-wide contracts. And without a neutral ISP that everyone has access to, the Internet just flat-out doesn't work. Because of that, I personally support government restrictions that force ISPs to respect my Right to Communicate. But if someone thought that was a bridge too far, I wouldn't say they were stupid. The ambiguity on that issue in the manifesto is on purpose; I want guiding principles rather than a step-by-step tutorial on every problem.

In regards to email, the same principles apply. Is the current system making it impossible for users to (voluntarily) communicate with each other? Spam doesn't count here, the Right to Communicate is not a right to force everyone else to listen to you. What is concerning about email to me are cases where untrusted IPs mean that multiple parties who want to communicate with each other are getting emails bounced and/or silently rejected with no way to fix the problem or bypass it.

If you wanted to make a case for regulating an email service with some version of Net Neutrality, you would need to make a case that email is a fundamental public utility that users/communities can't just avoid or bypass, that providers like Gmail/Yahoo are so big that they can't be broken up or unseated by normal means, and that they're currently failing to meet the standards that their size/power demands. I think making that argument about email providers is a lot tougher than making it about an ISP. But again, different people might reach different conclusions.