Sent items dissappear during an exchange migration between operators and secretaries due to mixes of Exchange 2010 and 2003 for example:
Current Enviroment 2003 : When I send from Exchange2003User1 onbehalf of Exchange2003User2 at the moment it puts the email in the Sent Item of Exchange2003User1
Secretary 2003 and Operator 2010 : When I send from Exchange2003User1 ( 2003 Mailbox ) onbehalf of Exchange2010User3 it replicates the above and puts the Sent Item of Exchange2003User1
Secretary 2010 and Operator 2003 : When I send from Exchange2010User3 onbehalf of Exchange2003User1 the sent email disappears ( does not get stored anywhere )
This means we will need to migrate all the operators before the secretaries move, and the secretaries can move one at a time after. Hope this helps now with UAT group!
In Exchange 2010 you can configure this server side to duplicate to both sender and from address.
Set-MailboxSentItemsConfiguration <mailbox id> [-SendAsItemsCopiedTo [Sender|SenderAndFrom]] [-SendOnBehalfOfItemsCopiedTo [Sender|SenderAndFrom]]
*NB Outlook will need to be in Cached Mode
Consider the following scenario. You use Outlook 2010 and are a delegate for your manager. Even though theDelegateSentItemsStyle registry value is set to 1, an email message that you send on behalf of your manager is saved in yourSent Items folder.