You literally can't have an email service that doesn't process your emails somehow. Spam filtering and phishing protection has to work on the content of the email, the act of sending email needs to read parts of it to send it. At the absolute least they need to "read" your email to store it's contents and send/display them.

If that is something you want to prevent, then i think using any hosted email provider is completely out of the question. Email in general might be unusable if that is the level of privacy you are looking for.

I normally hate parroting back the "if you don't like it then don't use it" line of thinking, but in this case it's the only real option. Sure they could offer a special service with no scanning, spam protection, etc... But they'd still need to store and "read" your email to work, and they'd still need to be able to do some analytics to protect their system from you (you could be a bad actor that would act in bad faith, and they need to protect against that to keep the entire service running). For someone that doesn't trust that they aren't going to just "read" your email anyway even if they say they only use it for some very limited things like spam protection, an additional layer of "we promise we also won't do this" won't change anything.

If you want absolute control over exactly what bytes are sent and where they go, host your own email service. Just like how if you want to be completely 100% absolutely sure that nobody is going to spit in your food, and you don't trust anyone else to not spit in your food, you need to cook it yourself.