Recently I typed up a new email message in TeamInbox. When I went to send it, Teaminbox had frozen and didn't send or save my message. That's a different issue, but to send my message I opened a new tab and copied over the message and to-email address so I could send it.

This worked, but I forgot to copy over the subject line so the email went out with no subject. It would be helpful to add a warning message when you attempt to send a new email but haven't filled out the subject line.