Question : Trying to use get-mailbox to list all mailboxes in forest

We are trying to use get-mailbox to list all users in our forest.  The way AD was setup was that we have a parent domain and 3 sub-domains.  When I run get-mailbox, I get all the mailboxes from our parent domain, but none of the subdomains.  When I run get-mailbox and specify a domain controller for one of the subdomains, I don't get all of the users in that subdomain.  For example, I only get 220 out of 242 users on one of the subdomains.

An example of our domains are

ny.domain.com
ms.domain.com
ar.domain.com

we also have users in domain.com

Thanks,
Robert

Answer : Trying to use get-mailbox to list all mailboxes in forest

Good question, I probably should have mentioned that they all do.  We have close to 2000 users on that domain.

The solution was to use the -IgnoreDefaultScope on the command line.