Deepest Sender is a blogging client that runs inside Firefox, SeaMonkey, and XULRunner.Deepest Sender is a blogging client for Firefox. What does this mean? Well, it means that instead of having to go to the Update page on LiveJournal/WordPress/Blogger/whatever, or loading up a separate client program, all you have to do is hit Ctrl+\, or click the button in your toolbar, and you can start posting.