I have TB 45.1.1 (on Arch Linux) with a Yahoo! IMAP e-mail account. Spam is automatically marked as Junk and moved to the Junk folder. Sometimes I have the following problems: 1. Messages are automatically marked as Junk although it's sender is in my Thunderbird address book. 2. When I remove the message from the Junk folder, marking it as "No Junk", it appears in the Inbox folder. (That's right.) 3. After a few seconds, the message is automaically marked as Junk again (but stays in the Inbox). 4. Thunderbird keeps marking the message as Junk. I noticed that Thunderbird does not keep marking the message as Junk when in offline mode. It looks like the Junk status online at Yahoo! is not updated. However, when I look up online at yahoo.com, there is no sign of a positive Junk status. I still have the option to mark the message as Junk. Any ideas?