QuickFilter Unreplied is a Thunderbird extension that adds an "Unreplied" function to the Quick Filter toolbar feature, which will automatically filter messages based on unreplied message(s).
QuickFilter Unreplied is an open source add-on designed to work with Mozilla Thunderbird 10.0 and later.
This add-on doesn't require you to restart the web browser.
How to Install in Thunderbird:
1. Right-click the link below and choose "Save Link As..." to download and save the file to your hard disk.
2. In Mozilla Thunderbird, open Add-ons from the Tools menu.
3. Click the Install button, and locate/select the file you downloaded and click "OK".
· Mozilla Thunderbird