I had this same problem a few times before, and called Verizon about it once, and after a long conversation about it, and them examining my settings, they said it was a Thunderbird thing. When this happened about a week ago, it was only for 8 hours or so, then it resolved itself without me doing anything. It's been 24 hours now, and when I try to get my emails (and also upon opening Thunderburd initially) I still get a message that says: Error with account [my email here] Sending of password for user [me] did not succeed. Mail server incoming.yahoo.verizon.net responded: (#AUTH003) Incorrect username and password. But I know the password is correct. I've reset it to itself and I still get this message. By the way I CAN send message. Just can't receive them. What gives?