I have a client who has their domain name registered through Network Solutions and their site hosted at GoDaddy. I checked at GoDaddy and they're not hosting the email accounts, so I asked the client and all they could tell me is they have Exchange. I'm trying to transfer the domain and hosting to a new host, but I don't want to mess up their email addresses at all. Since GoDaddy is not hosting the email and it's through exchange, will I be okay just transferring it, or will I need to do something with exchange to point to the new ip/nameservers/etc?
If you ensure that the DNS transfer keep the existing MX records (and other records related to mail) you should be just fine.
The MX records specify which hosts e-mail for the domain is sent to. If these hosts are also part of the domain, you should ensure that the records for those hosts are kept as well.
You can check the MX records for a domain here: http://www.scanmailx.com/index.php?option=com_php&Itemid=33&lang=en