For example, Tutanota says:
all user data is stored end-to-end encrypted in Tutanota (except for email addresses of users as well as senders and recipients of emails)
and Disroot says:
All emails, unless encrypted by user (with gpg for example) are stored on our servers in plain-text.
But also they say:
We use disk encryption on all data to prevent data leak in cases where servers are stolen, confiscated, or in any way physically tampered with.
And privacytools says, that on both this providers encryption is “Built-in”
So, how my Email encrypted when I send it from Tutanota account to Gmail account, for example? And how my disroot emails encrypted, if when servers stolen nobody can access data, and emails stored in plaintext?
I clearly understand E2EE in XMPP or Signal, for example. But when data is accessible from cloud at any time, it doesn’t look like E2EE.