Illegal host/domain name found - emails bouncing;

After using PhotoStream to post a picture on Facebook, my email asked me to confirm a password, which I've never had to do before. Now I can't send or receive email on the MacBook me.com account b/c an "illegal host/domain" message returns with the email. I don't know if I should be using the iCloud or my previous incoming mail server as the main server. Something changed after the PhotoStream attempt to connect the devices (iPhone and MacBook).

Anyone have any ideas? I read other posts, but didn't see the resolution.