To add mailbox permissions to other users in Microsoft Exchange Hosted Services (BPOS).
Add-MSOnlineMailPermission -Identity user@example.com -TrustedUser admin@example.com –GrantFullAccess True –GrantSendAs True
http://technet.microsoft.com/en-us/library/ee662271.aspx
Get Mailbox size settings from Microsoft Exchange Hosted Services
Get-XsHostedExchangeMailbox -SourceServer red001.mail.microsoftonline.com -SourceIdentity user@domain.com -SourceAdminCredential $cred -SourceDetail Full
http://blogs.pointbridge.com/Blogs/schertz_jeff/Pages/Post.aspx?_ID=85