I administer an exchange server for an organization that recently split up, and the side I went with (company A) got the exchange server. However, the other side (company B) got the domain name. Our current setup sends mail though mail.companyb.com, and I need to change it to mail.comanya.com.
I have to contact the DNS host have have them change the MX records, and also contact my ISP for reverse dns on the external I.P. address.
I have added the new domain as an accepted domain in exchange.
What else needs to be done in order to make sure that everything works correctly when we decide to throw the switch?