Question : Exchange 2003 - Cant receive or send external emails after ISP change

Hi

We have changed our ISP (external address from 56.xx.xx.22 through to 202.xx.33.xx.33). I have updated the MX and A records, and updated the external address in firewall. However I can no longer send or receive emails externally. Any help is much appreciated.
Do I need to do anything else.

Answer : Exchange 2003 - Cant receive or send external emails after ISP change

BTW - who is your ISP ?