Rated 3 out of 5 stars
As far as I can see although the button does not check/uncheck "Return Receipt" in the options menu it does work and will have the 'final say' once activated (ie pressed).
However if your account is set to request a receipt by default the button will not appear toggled. If you dont touch the button the message will request a receipt as per your default instructions. Toggling the button once will disable your default read receipt, and toggling again will set read receipt to off again! It is sort of logical and useable but can be confusing and I would prefer if this was fixed.
Almost a very handy little addon!
All mentioned issues are fixed in the next versions.