RH 6.2 to 7.1 upgrade

I’d like to upgrade my rh6.2 server to 7.1, mostly because the up2date software on 6.2 doesn’t seem to work very well and I’m falling behind in the patches & updates. My 6.2 runs sendmail as mail server for my office and also serves dhcp for my LAN.My question is: can I boot a 7.x cd and have the mailboxes, passwords, and soforth in 6.2 migrate to 7.x? I’d sure like to avoid having to set up all the pop users & passwords from scratch, and definitly don’t want to loose any e-mail!
Anyone been here?
Thanks