cannot send mail using outlook 2010

I have been using Outlook 2010 with my cox webmail for years.  Last Friday I was not able to send mail from Outlook but able to receive all my mail.  I could log onto my iPhone and send and receive mail just fine and could also send and receive from the mail program on my mac.  I have tried reconfiguring the outgoing account and incoming to imap from POP3. I can no longer receive or send from the POP3 connection but I can receive from the imap connection.  I still cannot send mail from either connection.  It tells me there is an issue with the server connection and to contact my isp provider for help.  I have tried contacting cox several different times and they have not been able to help me but tell me to call Outlook to fix.  Help!!!