Multi-column email view similar to kanban workflow

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

Organizing emails sucks in any email client. It's just overwhelming to manage, and if they're "out of sight, out of mind", so the likes of traditional folders and labels absolutely do not work well for me.

Describe the solution you'd like

I want to have multiple columns side-by-side to display the following:

• My true "Inbox" of yet-to-be-organized or actioned stuff (the goal being that I can achieve "inbox zero" by moving emails to wherever is appropriate for further activity, or action them right there and then, bypassing them being in a column).
• "Reply To"
• "Read Later"
• "Follow-up"
• "Waiting"

Obviously, once something has been replied to, it would be nice if was removed from column following a "Send + Archive" action ala Gmail.

Ideally, users would be able to add columns based on filters, labels/folders, senders, keywords etc.

Would be very cool if columns/boards/individual emails could be shared with others as "assignees", so we could collaborate on a reply together, or they could be designated as the sole person required to respond to it.

Describe alternatives you've considered

https://kanmail.io/, but it seemingly isn't maintained anymore, has a huge number of limitations, and importantly isn't a part of Nextcloud Mail, which is otherwise excellent.

Additional context

No response

No files, tests, or entry points are named in the issue. Start by narrowing the requested multi-column workflow, filters, email actions, and sharing into an agreed implementable scope; done would require that scope and its affected areas to be defined.