I am reporting a problem that occurs from time on one only of the accounts that I use in Thunderbird. The problem disappears for a variable amount of time when I close Thunderbird and then re-launch it. The full error message is the following: The POP3 mail server (mail.btinternet.com) does not support UIDL or XTND XLST, which are required to implement the ``Leave on Server'', ``Maximum Message Size'' or ``Fetch Headers Only'' options. To download your mail, turn off these options in the Server Settings for your mail server in the Account Settings window. When I notice that I have fewer mails than usual I restart Thunderbird and then they immediately start arriving. This would seem to be a TBird problem because I never have this problem with webmail, even while my mail is failing to be collected by TBird. By the way, the problem is 'silent' - by which I mean that the only time I see the error message is when I specifically try to collect my btinternet mail. My system is set to automatically download every 10 minutes but in this 'error' state I don't know if it is trying to do this or not. Other accounts continue to work normally.