I can sign into Outlook via Firefox. Thunderbird regularly downloads messages from there. When I try to send, I get a Server Not Found error or sometimes Unable to find server. I have deleted the outgoing server and reinstalled it. I have checked all the settings and have never found an error. This is a new problem (a few months old), and it previously worked well. I am running Ubuntu 12. Accounts at Yahoo and gmail work well. I am using Thunderbird 12.5. I have also added another entry for this server but it does not work either.