Use Export-Mailbox command
Exchange 2007 on Win2008R2 x64 can't use Export-Mailbox to pst, Exchange management tools must be installed on 32-bit OS.
Recipe:
one virtual XP with admin credentials ( also admin on Exchange 2007 )
IIS installed
Windows Installer 4.5
Outlook 2007
download http://www.microsoft.com/en-us/download/details.aspx?id=11876 SP3 version, 32-bit
start Management Shell:
Export-Mailbox -Identity "user" -PSTFolderPath "c:\user.pst" -DeleteContent //delete all emails in source/user mailbox and create pst file on c drive
Export-Mailbox -Identity "user" -PSTFolderPath "c:\user.pst" -EndDate "31.12.2012" -DeleteContent //delete all emails in source/user with end date 31.12.2012 and create pst file with all emails from beginning to end date
more about options: http://technet.microsoft.com/en-us/library/aa998579%28EXCHG.80%29.aspx
P.S. You must have permission on mailbox to perform export
Add-ON: if you need to check mailbox size for all users
Get-MailboxStatistics | where {$_.ObjectClass –eq “Mailbox”} | Sort-Object TotalItemSize –Descending | ft @{label=”User”;expression={$_.DisplayName}},@{label=”Total Size (MB)”;expression={$_.TotalItemSize.Value.ToMB()}},@{label=”Items”;expression={$_.ItemCount}},@{label=”Storage Limit”;expression={$_.StorageLimitStatus}} -auto