Change Mail Domain & New Server

Hi so I have a mail server running about 500 daily users and I wanted to know how to change the mail server to a new domain that we will migrate to and at the same time change to a new server

Will I have any problems or is it simply just moving the data over to the new server and then changing the domain to the new one in the install upgrade script

Do I need to manually change anything

What can I look out for and should do?

Thanks so much