Are you logging in from a network that is routed through an NTL / Virgin Media hub? We have one at home (we have Virgin Media cable) and my ntlworld email account has odd settings: pop server - no connection security, password transmitted insecurely smtp server - no username, no password, no authentication, no security I don't use that account very much, but when I do, it works fine. I assume that because I'm connecting to the server via Virgin's own hub and cable, it 'knows who I am' and therefore doesn't need to bother with a password and authentication; if I were to try to log in via another ISP, I would. So I'm wondering if, when your account was reset, it was set to expect secure authentication -- and when Thunderbird tries to connect using that protocol, the server doesn't respond. I suggest you check ''via your Virgin Media account online'' what the settings need to be (do it that way so that it knows you are one of their customers) and/or turn off the security settings in Thunderbird, as a test?