DNS Name for Exchange 2k7 Deployment

I an new at this topic and i hope some one can help me out. I am working on deploying exchange 2k7 for my company. I have a testing environment with a domain controller name mail.com and the exchange server on another box in the same domain mail.com. In my real environment the domain name i will have to install exchange on is vhs.local that this mean that the email address will for user will be user@vhs.local or is there a way around this? Thank for any help i get.