register site address.

i've already registered domain to internic (example abc.com) for mailing.
 
and i used site connector in exchange5.5 sp4 and winNT sp6 to connect another 
exchange site. in headquarter i use abc.com (site addressing) and the other 
site i use h1.abc.com and h2.abc.com .
can i use those sites of h1.abc.com and h2.abc.com (internet mail) without 
registering to internic? so everyone can send email to user@xxxxxxxxxx , etc. 
from hotmail or yahoo or another ISP,  or i have to register it (h1.abc.com and 
h2.abc.com) ?....

any comments would be appreciated...

Regards;
Amos D. Galiardo

Other related posts: