1. Let me persistently highlight text
2. Indicate things like “no need to respond” with a single tap, in a way that the recipient will understand
3. Predictively highlight action items in email I receive: "Can everyone take a look at the revised figures?" Etc.
4. Let me explicitly create an action item for recipients, like reading a legal release or voting in a poll; they can check off completion or answer poll, I can view status in a grid, spreadsheet-like view
5. Read receipts, also viewable in grid form when there are multiple recipients
6. For these action item group emails, let me select subset of recipients, like ones who didn't read email yet, or who voted No, let me email just them
7. Send and request money in the email itself, allowing recipients to use all sorts of payment methods
8. Keep track of which email addresses for a contact are getting bounced; prompt me to delete these and try resending to the next address instead
9. Let me send bulk email as individual messages, within the same grouped thread, rather than awkward bcc thing where it looks like the message was primarily sent to someone else
10. Gmail specific: it's ridiculous that Gmail android app -- and the new app, Inbox, too! -- won't let me compose to a contact list. Wtf is that about? What a workflow pain that is.