If your concern is being blocked, the best advice is to avoid any free email service and pony up for a paid one.
ProtonMail used to be the big one, but IIRC they had some controversy recently:
cointelegraph.com/…/proton-mail-exposing-activist…
discuss.privacyguides.net/t/…/24456
Other commenter already mentioned Zoho, but also mailbox.org.
Kissaki@feddit.org 8 months ago
I use posteo.de