cancel thread subscription for non-working emails

[haytham]

Hi,
When users sign up, they give their emails but with time the emails stop working for one reason or another. When that happens and they had subscribed to threads, I keep getting their thread notifications in my inbox which is time consuming and boring. I have to keep deleting emails.
What I'd like is a mod that would allow me to cancel thread subscription for non-working emails.

Thanks