Mail Server migration

[Eucke Warren]

Greetings all.

I have an old RH6(?) or 7 server running Postfix serving a number of users.  I am replacing it with a completely new server and a new RH9 build using Sendmail.  Am I being naive to assume that I can simply copy the /var/spool/mail folder, /home folder and the /etc/passwd file to the new server to preserve the existing users mail?  

Also, any other files I should be aware of that are needed that I have somehow overlooked.  I have been searching for FAQ's on this but do not seem to have stumbled on the right keywords.  Thanks in advance!

-Eucke