Mozilla Thunderbird does, and does it in very elegant a manner. For every folder in Mozilla Thunderbird, you can configure old messages (determined either by age or by the number of emails in the folder) to be deleted automatically. What is useful for the Trash folders is also great for RSS feeds, for example.
Remove Old Mail Automatically in Mozilla Thunderbird
To make Mozilla Thunderbird delete old messages in a folder automatically:
- Click on the desired folder with the right mouse button.
- Select Properties... from the menu.
- Go to the Retention Policy tab.
- Make sure Use server defaults is not checked.
- Check either Delete all but the last __ messages or Delete messages more than __ days old.
- Enter the desired time or message count.
- Keeping about 30 days or 900 messages in a Trash folder usually works fine.
- Click OK.