UI/UX suggestion for “Send Later”: It would also be very helpful if it were more obvious when a message has been successfully scheduled. In practice, I’ve accidentally re-sent messages a couple of times because the state wasn’t clear. Two ideas that might help:

After scheduling, automatically return to the previous view/folder (instead of leaving the compose window “active”).

Show a prominent, non-blocking confirmation (e.g., a banner or toast) that includes the scheduled send time and a quick link to “View scheduled message.”