Expose Snooze functionality via a Web API

[texttheater]

Is your feature request related to a problem? Please describe.

Nextcloud Mail's Snooze feature is great, it's a much-needed feature that IMAP unfortunately doesn't provide out of the box.

Currently, it is only available via Nextcloud Mail's own UI, and there is no compatibility with other software providing similar functionality.

Describe the solution you'd like

It would be awesome if other email clients (such as Thunderbird, via addons) could profit from Nextcloud Mail's server-side Snooze functionality and provide their own UI to use Nextcloud Mail as a Snooze backend.

So Nextcloud Mail would have to expose a Web API that allows clients to snooze and unsnooze messages and to query messages for whether they are snoozed and until when.

Describe alternatives you've considered

I'm currently using a Thunderbird addon but that only works on Desktop, for mobile I have to use Nextcloud Mail's UI. Both can share the same Snoozed folder, but they are not compatible in the sense that a message snoozed with one client will not be shown as snoozed by the other.

Additional context

No response

[ChristophWurst]

Thanks for the feature request. Interoperability would be great, I agree with you. @JohannesGGE spent lots of thought on this. Unfortunately there was no good way to achieve that back when we had the initial snooze implementation.

A small step into the right direction is https://www.ietf.org/archive/id/draft-ietf-mailmaint-messageflag-mailboxattribute-14.html, which will at least allow for an interoperable way to mark snooze mailboxes.

The big missing piece is still to find a way to store how long an email is snoozed.

I am hesitant to accept this feature request, because a Mail web API doesn't help Thunderbird, unless they specifically add support for Nextcloud Mail as complementary backend. Do you know if there are any such plans?

[texttheater]

I don't think integrating support into Thunderbird itself is necessary. As I wrote, a Thunderbird addon could do this. I currently maintain such an addon. I'd be very happy to add support for it to support Nextcloud Mail as a backend if there was an API.

[ChristophWurst]

This feature request has been accepted