Question : Updating Secondary MX Records

Our ISP just contacted us and advised that they are updating some equipment on their end.  As a result they want us to make sure that we can receive email from a new ip address that they gave us.  We are currently using Exchange 2003 sp2 with a Watchguard Firewall.  I am not overly familiar with how to set up Exchange.  I was not with the company when the original setup was done.  I need to know how I can check/make sure that we can receive email from the new Secondary MX server address that they are giving us.  Is there something in Exchange that I need to add and/or also in our firewall?

Answer : Updating Secondary MX Records

from now put your MX records and A record related to email server to minimum TTL value (half hour), this will guarantee that DNS replication will be fast

second Edit your firewall publish roles to meet the new IP address and replace it with all configuration of the old IP address