How to export PST files from SBS 2011

First you have to give the required access:

1. Start Exchange PowerShell
2. Type:  New-ManagmentRoleAssignment -Role "mailbox import export" -User ""
3. Close Exchange PowerShell
4. Restart Exchange PowerShell as Administrator
5. Type: New-MailboxExportRequest -Mailbox 'username' -FilePath "\\'server'\'share'\'filename.pst'"
6. You can also run a bulk export:
1. $Export = get-mailbox; $Export|%{$_|New-MailboxExportRequest -FilePath \\localhost\PST\$($_.alias).pst}

To read more go to: http://blogs.technet.com/b/sbs/archive/2011/05/09/how-to-import-and-export-mailboxes-using-pst-files-in-sbs-2011-standard.aspx