First I’d like to suggest Newsletter as a Topic in the Help Contents and as a separate category here in the Forum.
Second: I’d like to be able to Delete a newsletter before it sends. I use the newsletter feature to allow people to get each post on my blog by email as it’s published.
Today I published a post that should have been dated for 2 years ago but accidentally published it with today’s date. I realised my mistake before it was actually sent and hoped to delete it. I ended up writing an explanatory note at the top of the email as I couldn’t find a way to delete.