I am English and when using my live.co.uk email has always used English UK but yesterday it suddenly started underlining my English UK spellings. If I type English US spellings as a check they are no long underlined. It happens when using my emails in the new outlook.com system. It doesn't do it in old messenger based Windows Live Mail, although it did briefly yesterday. I managed to correct it. I can't correct it in the outlook.com system. It worked okay in outlook.com system until yesterday, I find this extremely annoying & don't want to have to go to Gmail.