Welcome to ITKE
Rebooting the firewall may fix the issue. The MX records are stored in the domain
name servers (DNS) as a record. The best way to test this is to go to http://www.dnsreport.com/
and run both tests on your domain name (your whatever.com name). That
will let you know if there are any DNS MX records and what they are. If
there is a common issue is will also give you some usefull information.
If it is in fact a DNS MX issue you can run a WHOIS lookup to see who
maintains your DNS records and that can be done at Network Solutions
www.networksolutions.com/whois/index.jsp That should give you at least a
email address to deal with if not a phone number.
Also contact Godaddy support
Hope this helps.