How to change Apple Mail's RSS preferences

Question

How do I change or add to the Apple Mail RSS preference to retain messages for three days? The default choices in the pull down menu are 1 day, one week, two weeks, etc. Do I need a terminal command?

Answer 1

From my own testing, it appears that the setting RSSAutoDelete in ~/Library/Preferences/com.apple.mail.plist controls this feature. Try running the following command in Terminal.app:

defaults write com.apple.mail RSSAutoDelete -int 3

The GUI settings are "Manually", "after one week", "after two weeks", etc., which appear to correspond to the values 0, 7, 14, etc. It's a reasonable guess that setting it to 3 might make Mail.app delete messages after 3 days.