[Users] How to hide sender IP address and host name?

[Removed GDPR]

> You use gmail, so some would argue that you left your privacy
> concerns at the door anyway.

I am currently looking for alternatives actually, so this is part of a
bigger reaserch :) Unfortunately I can't find a single online service
provider who can guarantee me that their systems are clean from
proprietary malware (like Intel ME, proprietary BIOS etc) and without
that merely migrating to yet another "owned" system hardly makes any
sense. Can you recommend anything along these lines?

Otherwise with end-to-end encryption one can pipe through any server I
guess and it wouldn't really matter who the carrier is. BTW, as a
side note, I would rather assume that Google have done a much better job
regarding cleaning their systems than most others:

https://www.youtube.com/watch?v=iffTJ1vPCSo

But again - that is a separate discussion I suppose.

The question how to hide the sender's IP address from the receiver (not
from the server) still remains.