For Firefox their are so many blockers "Ghostery" etc.
However their are some new add ons that allow you almost (or so they claim) anonymity.
I’ve been using GMX since when it was in English. LOL
It is a German email provider. The website initially was also in English, but they dropped that years ago.
When I signed up, it allowed mail to be received, but not sent, on the free email service. I don’t know whether they have changed that.