Thanks for the informative answer.

The business model seems to be subscription based which i like(decently priced imo).

i suggest you looking into supporting external mail clients like k9/fairemail. Emails being encrypted at rest would be big.(People like to keep their stuff private even from the provider). Having a web app is nice tho.

i hope your ventures into this become succesful.

what is the business model for this service?

i couldnt find a privacy policy.

Sorting emails like this is really useful.