Do you have Internet access?
Are ports 25, 110, 80, 443, and any other bound ports open on your firewall(s)?
Are all of your PORTS bound to the proper IP address(es)?
If you moved to a new box, and a new operating system, do you have new IP ADDRESSES? If so, did you change them in all of your BINDINGS, DOMAINS and SMTP settings?
Are your DOMAINS bound to a valid IP address?
Is your OUTBOUND SMTP properly configured to use either the DOMAIN's IP ADDRESS or a selected IP address?
If you are not using IPV6, did you DISABLE it - EVERYWHERE?
This is just a start, there are many other places to look.
Phonr: (773) 491-9019
Phone: (224) 444-0169
E-Mail and DNS Security Specialist
Network Security Specialist
Customer Service Portal: https://portal.chicagonettech.com
Security Blog: http://networkbastion.blogspot.com/
Web and E-Mail Hosting, E-Mail Security and Consulting