My servers always show up on the list.
Did I say you were banned? I was explaining what being banned from the master server is.
it can be undone?
Of course, you would have to
buy a new key contact Badspot to undo the process. Usually if you are banned from the master server, most reasons are: key failure, master server spam (sending fake data / replicating it), or using the wrong version of BL (sometimes Badspot bans people from posting their server to the master server for using v20 because it posts on the v21 master server, but also v21 clients will break if they go onto a v20 server, it's happened before)