A. Mailboxes can be viewed via the Exchange 2007 Exchange Management Console, Recipient Configuration, Mailbox area. However, this doesn't give all information available. Using the Get-MailboxStatistics cmdlet, you can get detailed information about a mailbox size and limits. For example,

Get-MailboxStatistics jsavill | format-list
AssociatedItemCount : 102
DeletedItemCount : 11
DisconnectDate :
DisplayName : John Savill
ItemCount : 13439
LastLoggedOnUserAccount : SAVILLTECH\jsavill
LastLogoffTime : 5/10/2007 2:08:57 PM
LastLogonTime : 5/10/2007 2:08:57 PM
LegacyDN : /O=SAVILLTECH/OU=FIRST ADMINISTRATIVE GROUP/CN=RECIPIENT
S/CN=JSAVILL
MailboxGuid : 80eb96b7-1401-4e6a-a0f8-1ad3eac3a220
ObjectClass : Mailbox
StorageLimitStatus : BelowLimit
TotalDeletedItemSize : 148440B
TotalItemSize : 590465228B
Database : DALSXC02\First Storage Group\Mailbox Database
ServerName : DALSXC02
StorageGroupName : First Storage Group
DatabaseName : Mailbox Database
Identity : 80eb96b7-1401-4e6a-a0f8-1ad3eac3a220
IsValid : True
OriginatingServer : dalsxc02

To get more detailed information on a per-folder basis, use Get-MailboxFolderStatistics instead of Get-MailboxStatistics.