Exchange 2007: easiest way to grant permissions on multiple mailboxes?

Question

I'd like to create an account (named "Test") and allow this account have READ permission on multiple users' mailboxes(and calendars).
I've read the article on http://technet.microsoft.com/en-us/library/aa996343.aspx.  I know I can use the following command:
Add-ADPermission -Identity "Mailbox Store" -User "Trusted User" -ExtendedRights Receive-As
Question #1: What if I want to add this permission to ALL mailboxes?
Question #2: What if I want to add this permission to a group of mailboxes?  (such the users in an OU or a department)?
Question #3: Is this command alone enough the give the READ permissions to "Test" account?  Do I have to make "Test" account a "View Only Administrator" as well?
My ultimate goal is to use least commands to give least permission to the "Test" account.  So the "Test" account can read other users' calendar information via WebDAV interface.
Thank you very much!
Michael
P.S.
On Exchange 2003, I can do the following to assign "receive-as" permission on mailstore level.  But I couldn't find an equivalent way on Exchange 2007.
Step 0 Make "Test" a View-Only Administrator
Step 1 On the exchange servier, open the Exchange System Manager.
Step 2 Navigate to Administrative Groups > First Administrative Group > Servers > First Server >
Mailbox Store.
Step 3 Right click the mailbox store and choose Properties.
The Properties window displays.
Step 4 Choose the Security tab and click Add.
Step 5 In the Enter the object name to select field, enter the name of the account that you want to use.
Step 6 Choose Receive As to grant Receive As permissions to this administrator account on all mailbox stores
against which you need to access calendar information.
Step 7 Click OK.
The account that you set up now has full permissions to log in to the mailbox store.
Ref: http://support.microsoft.com/default.aspx?scid=kb;EN-US;821897

Answer 1

Hi,
I understand that you would like to grant one account have permission to view all mailbox’s calendar and a group of mailbox’s calendar.
Regarding this issue, please run the following command to resolve this issue.
Grant Test have permission to all mailbox
Get-mailbox | Add-MailboxPermission –user “Test” –accessright Fullaccess
Grant Test have permission to a group of users
Get-mailbox –OrganizationalUnit “group name”| Add-MailboxPermission –user “Test” –accessright Fullaccess
Thanks
Allen