Exchange 2010 in Domain Environment with Stub Zones

Hi,

i am planning to deploy exchange 2010 in my network , my network is as follows

Have 1 Head Office with 2 Branch offices

head office and 2 branches are having windows 2008 R2 Domain respectively each has its own active directory and forest
Each site has a domain functional level = Windows 2008 R2

2 branches are linked with the head office via radio links and are two way trusted domains with head office using stub zones

my question is if i deploy exchange 2010 in Head Office will the 2 branches be able to use it as well 

i mean will exhange 2010 be able to create mailboxes for users in Active directory of both branches? and will my users in 2 branches be able to access exchange 2010 server for their daily email?

please guide.

Thanks & Regards
Nabz.