Your mail client should generally not be attempting to contact outlook.com; I am guessing that your email account has not been set up correctly.
Apple provides a setup assistant to help you configure Mail.
Try http://www.apple.com/au/support/macosx/mailassistant/ and see if that helps. Note that if you cannot connect to the internet, your mail will not work either.
If mail has been working for you before but suddenly started showing this error or if you are using a different email client from Mail, then please reply with more information.