I have been using Nis 2011 since it was in beta and have been using Thunderbird 3.1 beta the whole time. Just starting today NIS has started to stop all incoming and outgoing email through thunderbird. I can get my email through web mail but it is just to slow and I like using Tunderbird. I am using win 7 ultimate with NIS 2011 and Thunderbird 3.1. If anyone has an answer please let me know.