Domain Name Transfer - Cannot get emails now

During the process of integrating our current domain name from Network Solutions to Comcast, I can no longer get our emails through Outlook.  After I provided Newtork Solutions with our CNAME and they made the change in their servers, our email is unaccessible through Comcast, through Outlook.  I am on my 3rd ticket # and am not getting any response, or remedies for the problem, with Comast IT.  Can you help please?  We are a business, and need to function with emails, which we have not had now for 4 days.