Preview in email notification

[bedhub]

When receiving a new email notification i want to be able to see some initial information from the received mail so i can decide if i should read email now or later.

AC

• The notification shows, subject, sender and recipient.
  • The sender is the sender name if available otherwise the email address
  • The recipient email address.
  • Subject from the Mail entity
• The information is not available to any external push notification provider.
• There is a settings page to configure notification behavior Settings/Notification
• There is an option to show/hide extended notification information, called "Notification content/Mitteilungsinhalt" with the following options
  • No sender or subject
  • Only sender
  • Sender and subject
• If preview is "Only sender" we show sender/recipient information.
• If preview is "No sender or subject" we show "New Tuta message" received.
• The settings is configurable per user per device
• For newly added accounts the setting is "Sender and subject" by default
• For existing stored accounts the setting is "No sender or subject"
• Near the preference there is a help text that links to a support entry that explains background data access.
• Data to decrypt the extended notification is secured with system key chain
• When user selects "No sender or subject" data is removed

Notes

• Option1: Add encrypted subject, sender, receiver to MissedNotification
• Option2: Download mail and decrypt (assuming that the mail has not been moved)

For showing the preview we prefer Option2 and try to download/decrypt the email.

Tasks

• [ ] #6959
• [x] https://github.com/tutao/tutanota/issues/6957
• [x] #7072
• [x] #6608
• [ ] Add a preference option in settings
• [ ] Change default for new logins
• [ ] #7222
• [ ] #7223

[Chirunos]

I think an option to disable this would be nice (or maybe even better, make this opt-in), since many people configure their lock screen to show notifications but wouldn't necessarily feel comfortable with this additional information also visible

[C8opmBM]

I see the roadmap and this pops up first in the list. TBH, this is the top of the list priority for me as well. I really hope it could be implemented. Fingers crossed!

[polzon]

To piggyback off of this request: if I tap on the notification, it should open up the previewed e-mail rather then my inbox where I have to hunt down which folder it went to, or what e-mail notification I even tapped on.