Just joined so I hope that I am posting the correct location.
I have found that the above named add-on no longer works with the latest version of TBird, I realise that Firefox and Thunderbird are directly linked or should I say , that was information given to me.
I found that add-on was a very useful way of not going above my quota on my IMAP email account.
If I am incorrect on any of the information. Please correct and possibly point me in the correct direction.