[yonrg]

This categorization seems to be based on one dimensional thinking (not in a bad way).

If you bring in more dimensions you end up with something like a taxonomy where an email contains a message and maybe also a todo or something else and may have more attributes around those identities. Then you can filter by those. I do not use that personally but I see there is no reason to define an email as a todo item.

Also, as an email is just a storage for data, you could (mis)use it as a storage backend for a file system (see fuse) or backup solution.

So an email can be everything you want.

[chris-orgmenta]

You end up with a graph. Entities are the nodes, and the entity-relationships are the edges.

An email is always a message, nothing more. Tasks, events etc. can be derived from it, but the email itself is not a task or event. This isn't arbitrary, these boundaries are clean as heck (again of course, with the 'IMO' caveat. I don't care to convert anyone here).

[ethanbond]

Very interesting model — what do you actually do with this conception? Do you have software that helps you reason about your inbox/rest of life this way?