By default Delegates/users sending emails on behalf of managers/shared mailbox do not store sent emails in “Sent items” of shared mailbox. It gets saved on the “Sent Items” of the sender. For example User 1 (Delegate) sends email on behalf of User 2 (Manager), the email gets saved in sent items of User1 mailbox. This may not be acceptable in certain situations such as Support mailbox where many people manage single mailbox for support activities. They might require all emails sent from shared mailbox to be stored in sent items.
Exchange 2010 has additional option to change this behavior. This is supported from Exchange 2010 SP2 RU4 and upwards.
Get-MailboxSentItemsConfiguration – To fetch the current setting on a mailbox
Set-MailboxSentitemsConfiguration – To set the values.
Values SendAsItemsCopiedTo and SendOnBehalfOfItemsCopiedTo can be set to following parameters
Sender: This is the default value.
SenderandFrom: with this value set, Emails which are Sent using send as or sendonbehalf will be saved in shared/manager mailbox.
From: This option will store emails only in the sent items of Shared/Manager mailbox. However looks like this does not work as expected.