Yes, but the key is stored in your iCloud backup if you use it. As soon as you disable iCloud backups it will roll the key for iMessage and they will be effectively E2E encrypted.
When Messages in iCloud is enabled, iMessage, Business Chat, text (SMS), and MMS messages are removed from the user’s existing iCloud Backup, and are instead stored in an end-to-end encrypted CloudKit container for Messages. The user’s iCloud Backup retains a key to that container. If the user subsequently disables iCloud Backup, that container’s key is rolled, the new key is stored only in iCloud Keychain (inaccessible to Apple and any third parties), and new data written to the container can’t be decrypted with the old container key.
> Yes, but the key is stored in your iCloud backup if you use it. As soon as you disable iCloud backups it will roll the key for iMessage and they will be effectively E2E encrypted.
Assuming this is true, you still don't know what people on the other end will do, meaning it is never actually E2E encrypted.
E2E usually means from endpoint device 1 (my iPhone) to endpoint device 2 (my friend’s iPhone). What the other person will do with it doesn’t factor into the conventional definition of E2E.
No, conventional definition is actually both: from endpoint device 1 to endpoint device 2 and from endpoint device 2 to endpoint device 1. If device 2 has backups in question enabled, there is no E2E anymore.
