I'm actually a customer of Tutanota, and their product has been pretty good in the last ~2 years I've used it.
Short of hosting your own email, I can't think of other email providers as secure as tutanota. They tick off a lot of boxes: open source, hosted in Germany, encrypted mailboxes, DKIM/DMARC support...
The only feature that might give people pause is that their search functionality isn't great. I have pretty low volume of emails to my personal inbox so it doesn't matter, but it might be frustrating to use as a work inbox.
Short of hosting your own email, I can't think of other email providers as secure as tutanota. They tick off a lot of boxes: open source, hosted in Germany, encrypted mailboxes, DKIM/DMARC support...
The only feature that might give people pause is that their search functionality isn't great. I have pretty low volume of emails to my personal inbox so it doesn't matter, but it might be frustrating to use as a work inbox.