Allow (encrypted) app backups e.g. via SeedVault

[Diapolo]

Checklist

• I have used the search function to see if someone else has already submitted the same feature request.
• I will describe the problem with as much detail as possible.
• This issue only contains a request for one single feature, not multiple (related) features.

App version

6.301

Problem you are trying to solve

Current K-9 Mail app doesn't allow encrypted backups via SeedVault (backup App for Android, integrated in LineageOS or CalyxOS, see https://calyxinstitute.org/projects/seedvault-encrypted-backup-for-android).

Suggested solution

Allow encrypted app backups :).
See https://github.com/seedvault-app/seedvault/wiki/FAQ#why-do-some-apps-not-allow-to-get-backed-up for a description of the problem and see this sample how Transport (Android app for public travel) implemented it: grote/Transportr@4dc38f4

Screenshots / Drawings / Technical details

No response

[cketti]

Duplicate of #3857

[Diapolo]

@cketti Not exactly, but anyway. Would be nice, if you could take a look at the linked implementation ;-). Any interrest in adding the support? Am 25. August 2022 15:06:34 UTC schrieb cketti ***@***.***>:

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Duplicate of #3857