They’re not blocking you because they hate you.

Really. They’re blocking you because you’re doing something that is triggering their blocking mechanisms.
This has happened over and over and over again. Some political or activist website sends out an email that gets blocked by some large ISP and the political site turns it into a giant crisis that means the ISP hates them or is trying to shut them up or is trying to silence their message.
Except that’s not what is going on. The folks at the large ISPs who handle blocking and incoming mail are incredibly smart and conscientious . They take their jobs seriously. They, both personally and corporately, want their customers (the end recipients) to receive the email they want. Additionally, they do not want to deliver mail that the recipients did not ask to receive.
In almost no cases is the block a particular activist site encounters a result of the ISP not liking the content of the email. If an activist site is being blocked it’s due to complaints or reputation or something that ISPs measure and block on. Some person at the ISP didn’t read your email, decide they didn’t like what you had to say and then block that email. That email was blocked because something related to that email triggered the thresholds for blocking.
Of course, as with everything online, there are caveats. In this case it’s that the above statements really only hold true for large ISPs in free countries. There are some countries in the world that do block email based on content, and that is dictated by the government. Likewise, some small ISPs will block based on the guy in charge not liking the email.
Generally, though, if an activist site is being blocked by a large ISP in the US or other free countries it is because their mailings are somehow not complying with that ISPs standards. Instead of starting an email campaign or blog campaign to shame the ISP for suppressing speech, it is much more productive to actually contact the ISP in question and find out what went wrong.