external mailing for exchange

can i test to send e-mail using the configured exchange server w/out a domain name, to send e-mail to my yahoo email accnt or AOL email accnt?

is it ok to install the exchange server even if you only have a static ip address and no damain name?(e.g. domainame.com, can i test the messaging system with this type of configuration?

im still on the process of implementing this to my friends company and im still not sure if i can do this to configure an exchange server