I use Kubuntu 11.10 and also use Thunderbird 10. I'm not noticing the same issues as yourself as I use Gmail, Yahoo, Inbox and Hotmail.
Currently I have confirmed the following : Gmail - Send and Receive Yahoo - Receive only at the moment Hotmail - Send and Recieve Inbox - Send and Receive Webmail - 1.4.6 Yahoo - 1.5.6 MSN - 1.3.4 Rob..
