Good response, George.  I encourage everyone who wants an anonymous email account, such as Protonmail, to create and only access via Tor.  Remember, your IP address is always logged and the minute you login to any account or access any website with your real IP address, it is logged.  Who knows how long until those logs are erased or overwritten.  If a court order does subpoena your Protonmail info, they should gain no IP addresses that can trace back to you if you only accessed the account via Tor.

For those that use Signal, if the police take your phone while it is unlocked, they will probably see your Signal messages and the phone number of who you were contacting.  So much for anonymity unless that person used a burner phone.

Session seems like the best bet.  Session is new, so this Troll_of_Truth has not explored Session yet, but when I do will provide updates.

In summary, it seems that using Tor is still the most secure method for internet activity.

As far as that Harvard student, Eldo Kim, who got "caught using Tor," it was because he confessed.  The police assumed that a campus bomb threat might just be made by a student, then the police saw that the bomb threats came from Tor and looked into anyone using Tor at the time.  Kim confessed to using Tor and making the bomb threat.  The last sentence in that article states: "And to think he could have had gotten away with it had he just used the wireless internet at a local Cambridge coffee shop."  This is true.  An anonymous coffee shop would have provided him with a bit more anonymity, though police could have checked cameras to see who was logged in during the time of the alleged crime.

The police had no idea what Kim was doing on Tor.  Kim could have just kept quiet and maybe walked.  Similar to the polygraph where the number one rule is make no confessions.  However, Kim was cornered and confessed and that is what did him in.

Indeed, corporations are required to comply with court orders in their respective countries. Note, however, that since the time when ProtonMail was compelled to record the IP address used by a particular account to log in, it has won a legal challenge. "[T]he Swiss Federal Administrative Court confirmed that email services cannot be considered telecommunications providers, and consequently are not subject to the data retention requirements imposed on telecommunications providers:"

https://protonmail.com/blog/court-strengthens-email-privacy/

While Signal must answer court orders, it retains very little information to hand over.

Security and anonymity are not the same. ProtonMail and Signal both provide excellent security, but to use them anonymously requires particular care. One can use a ProtonMail account anonymously by creating it over the Tor network and only ever accessing the account via Tor.

Signal can also be used anonymously, but this poses special challenges, because Signal requires the use of a telephone number.

Among messaging apps, Session may well provide the best combination of both anonymity and security.

Tor makes it possible to use the internet anonymously, although there are ways that one's anonymity can be compromised while using Tor. The case of the Harvard student who sent a hoax bomb threat using Tor Browser comes to mind:

https://www.forbes.com/sites/runasandvik/2013/12/18/harvard-student-receives-f-f...

It appears that no company is immune to a court order from law enforcement for the data that the company retains. 

https://thehackernews.com/2021/09/protonmail-shares-activists-ip-address.html

https://www.zdnet.com/article/signal-unveils-how-far-us-law-enforcement-will-go-...

https://signal.org/bigbrother/santaclara/

The only option is for these companies not to retain ANY data (no IP addresses, login info, etc.).  Maybe the Session app and Tor are the two most anonymous services.  Thoughts?