Automatically Delete Unwanted Cookies in Firefox
I prefer to not have cookies stored in my browser, but it’s impractical to not store any cookies since this would require repeatedly logging in to authenticated sites that I frequently use. A simple solution in Firefox is the following:
From the Edit menu, choose Preferences and then click the Privacy tab. You should see a dialog similar to the following one:

Check the “Accept cookies from sites” checkbox. For the “Keep until” setting, select “I close Firefox”. The latter is the key - it will erase all cookies from Firefox whenever you close the program. Of course, we don’t want to erase all the cookies, so click the “Exceptions…” button on the right and you’ll see a dialog similar to the following:

Just type the name of the web site you want to allow in the text box and click the “Allow” button, and Firefox will add it to the exception list so it won’t be deleted when you close Firefox. You can add a full URL such as www.MySite.com, or just the domain name MySite.com to allow cookies for any host in that domain. You an also add sites you want to disallow any cookies from by clicking the “Block” button.
I have about 30 sites that I allow Firefox to store cookies for, but this technique has helped me avoid accumulating tons of unwanted cookies in Firefox. I hope it’s helpful for you.
