Image via WikipediaThis is a feature request.
When you get into compose mode - and that is a mindset, a killer mindset - you should have two options. One option would be that your message - no subject line allowed - would be limited to 140 characters. The upside would be the receiver would not have to click to read it. Your entire message could be read and replied to immediately from the inbox.
The various email providers would coordinate to commonly have that feature. This feature would be like FedEx for email: expedited service.
There might even be a Short Message Inbox like there is now a Priority Inbox. That would be swell.
Save on clicks, save on space, save on time.