I can recommend the folks over at Migadu (https://migadu.com https://migadu.com) which is a small Swiss email host. Their support is very responsive and I never

I can recommend the folks over at Migadu (https://migadu.com https://migadu.com) which is a small Swiss email host. Their support is very responsive and I never had any issues while there. I was also a Fastmail customer and I can recommend them too. I actually had all of my email for the last 10 years in one mailbox (100K+) and Fastmail didn't even blink most of the time handling it. Performing an action on every email such as setting everything to "Read" would take ~10 seconds but that's to be expected for the amount of work being done. Currently I'm using G Suite for the additional services but I never had an issue with the two I mentioned above.