@mihael Actually there is an undo button ! I didn't noticed it because it is not avalaible in my BQ E5. I assume it is because I still use the Canonical image. But I have UBports in my BQ M10FHD and there is an undo button. I agree that it is even better since it notifies and let you undo in case it was a mistake. I think it is the perfect solution for most of the actions.
I still think that a confirmation dialog after sending a message (or any action that you can't undo) would be good. Its a good thing to know that an action went successfully and that nothing crashed, especially now we are testing this new (and so good !) app.