Of course. Your personality and consciousness are entirely defined by three things: Your memories, your current surroundings, and the current chemical state of your brain/body. Changing any of those will change your logic and reasoning because reasoning in a vacuum is something only computers do.
For examples of changes that would drastically alter the thought process of even the most stoic, rational person, here:
Memories: Amnesia from brain injury
Surroundings: Being trapped in a coffin full of centipedes
Brain chemistry: Being high on methamphetamine
Any of these things will immediately demonstrate that we are not computers or logic machines.
mailbox.org is quite good. I prefer them over protonmail because I want to use my own client. If you don’t care about using a web UI, use protonmail, otherwise use mailbox.org. you can also take a look at tutanota