I have a work e-mail account (IMAP) that works just fine. But sometimes when I recieve an email and I reply to all and thunderbird confuses all the addresses. Even though thunderbird displays a warning saying that the sending address desn't match the replier sometimes it has got me in some trouble because i sent some mails like it was from another email. I have noticed that this problem happens when I'm in CC and there's only one user in the "to" box. I send you a couple of pictures that explains it better. In red is the original sender in green is the "to" reciever in blue is me, in CC When I put reply to all, the sender appears like the main reciever "to" (red), the original reciever appears like the sender (green). And I appear in CC. As you can see, the yellow warning appears, but is a mistake