Specifically, these things:

1. When I delete a message, skip to next message that is older than the current one
2. Add next/prev buttons in the message view, to make it easier to navigate between messages without going to message index
3. When message is sent sucesfully, either add a link that goes back to message index in the success message, or render message view directly and show the success message above it

Thous would save all players several needless clicks.