Kolab Now is another open-source email service
with its servers completely hosted and managed in Switzerland, just like ProtonMail, so your private data is never crawled.
But between the ability to use Thunderbird or similar email clients for fully-encrypted messages and the storage of your content in a country as secure about data as Switzerland,
the sacrifice in security for the features Kolab offers might be one of the best
tradeoffs in email today.