I’m also looking to migrate and was recommended this service when I asked a similar question to OP. https://www.migadu.com/index.html

Unlimited inboxes. You’re just limited to inbox space, but you can have multiple domains.

I’ll be moving over to them when my current subscription runs out with my current provider

SSH is the answer.

Another approach would be to use WSL (windows subsystem for linux) and basically just communicate from one Linus box to another