I manage multiple email accounts in my Thunderbird. With one of them I have the problem that Thunderbird tells me that I have new mails when I don't. This means the dock icon appears saying "(emailaddress) has 14 new messages" (it is always 14) and in the Thunderbird window the "heading" (don't know what it is called) of the mail account turns blue ALTHOUGH no number for unread messages next to the name appears. This happens again and again at irregular intervals of a few minutes to several hours. I don't know if it matters but the problematic email account is a Gmail one while none of the others is. I already tried deleting the .msf files and compacting, did not help.