Outgoing Comcast Email is being marked as spam; Multiple calls to Security Assurance have not helped

My wife and I both have comcast emails.   We both are now in a situation where we can receive emails from all sources but cannot successfully send outbound emails outside the comcast domain.   The problem started when we were traveling in Australia so there was a thought that it was a location issue but now we are back in home in the States and the problem still exists.   We have called Customer Security Assurance 7-8 times and even level 2 security doesn't have a clue and haven't been able to troubleshoot the problem (when they call you back which doesn't happen).   

We use Apple Interface and Outlook but also have used the comcast web based email with the same result.