Interesting how many there are.
Basically wrappers:
- Boxy Suite (simple wrapper)
- MailPlane (wrapper with tabs)
- Shift (window for multiple communication apps)
- Wavebox (window for multiple communication apps)
Wrappers with heavily re-done themes:
- Superhuman (fancy minimalist ui)
- Tempo (fancy minimalist ui)
Unique UIs:
- KanbanMail (what you think it is)
- Sortd (also like kanbans)
- Spike (turns email into conversations)
Full-blown clients (not really Gmail-specific)