Every day, millions, if not billions of emails are sent. Billions of grains of sand, slipping through the fingers.
Nobody has the time to trace your email down unless it has a clear financial value (ie, parading you in front of cameras to keep their budget going), nor do many have the capacity to do so and even less will have the inclination by the time you factor in that there almost always needs to be a crime committed or as a process of committing a crime.
Don't believe the hype - it isn't even remotely true that many who are tech savvy can figure out where it came from. That is utter fucking bullshit. If I sent an email to someone through tor and any email service.. unless I'm front page news if what I'm doing.. no, just no. No interest.
Even if you email me with the easiest tell - from your isp's free email, Yeah, I'll have your isp immediately - but I've still got to convince your ISP to give me your details or obtain them illegally, myself. Red flag for 99.9999% of the population. Even higher percentage once you factor in the "give a fuck" element. Back in previous times, you could do more with the IP - often boards would publicly show the the IPs of posters, allowing higher correlation.
People like to talk about how unsafe they are on the internet and how big brother is watching - well, reality check, your lives aren't on big brother's radar. There is an element of truth to the idea of AI doing increased correlation in the not too distant future but again, you're not doing the shit they're looking for. Stay away from children and keep your crazy religious beliefs to yourself.
Or better still, just don't send that email - doesn't sound like you're wanting to do something "good".