I am giving Thunderbird's RSS abilities a try. One annoyance is that I cannot apparently tell Thunderbird to keep quiet when a new RSS post is downloaded, but reserve the playing of sounds only for new emails. The option is under "Incoming Mails," but I keep getting bipped like crazy, and I am having to assume it's due to RSS post receipt. I don't see any way to control this in the Config Editor. The user should be able to control sounds separately, including specifying one notification sound for new emails, and a different notification sound, if the user wishes, for newly received RSS posts.