Why doesn't Thunderbird block spam and junk mail? It often tells me that "Thunderbird believes this message is Junk," and I right click "Mark" and tell Thunderbird the message is "Junk," but the sender is never blocked. How many times must I tell Thunderbird that a sender is spamming me? Why is it so difficult to block a sender who is spamming me? With other email clients, just one marking of "Spam" is enough to block that sender? How do I tell Thunderbird to block a spammer?