“Reply Later” queue

One of the neat ideas in HEY is a “Reply Later” feature paired with a “Focus and Reply” flow. Basically, you can quickly mark an email as one you'd like to reply to, and it gets set aside into a little pinned UI. Then when you're in the writing mood, you can choose to “Focus and Reply” to each email. They get queued up in a sort of feed with your reply next to them. Once you finish one, you move onto the next.

It's kind of an opinionated workflow, but matches how I personally use my mail: a reading context, and then a replying context. I'd be interested in implementing something in Mail.

To keep it cross-platform friendly and not just dependent on a local data store, we could potentially use labels/folders to mark the emails that need to be replied to under the hood.

Here is more info about the HEY features:
- https://hey.com/features/reply-later/
- https://hey.com/features/reply-mode/