I've taken over this add-on from @Daniel Hood, and it's now available on my site, Atelier Aphelion, for purchase and download. All future versions will be there, as well.
If you have a current license for this add-on, you can register it there (instructions are available here). You'll get a license from me (terms here), for the remaining duration of your original license, plus another 30 days - just a friendly gesture because of the inevitable delays caused by the hand-over.
My plan is to review and update this add-on to address any outstanding issues. Because I've taken over almost all of @Daniel Hood's add-ons, it might take me a while to get to this one.
To improve support, the requirements for this add-on have been updated:
Introduced the option to suppress persistent emailing. If the suppress option is enabled, your users will only receive one email (until they read the thread) like XenForo normally does by default but will continue to get "alerts".