It would be nice if the send check message could append a message at the top of the email to indicate that it is just a test and not the final email.
I have a few people who like to see tests before they go out. There's no way for them to know which is the test and which is the actual email that is sent.
It would be even better if the message was customizable. IE. allow me to put "See paragraph 3. is that the wording you wanted?"
It would also be nice to be able to set up a test group of subscribers and send to that group without having to type in their email addresses each time.