Enabling ‘save to sent items’ for a mailbox ensures that messages sent using send as permissions are saved to the sent items folder of the mailbox (in addition to being saved to the sent items folder of the sender’s mailbox).
To configure save to sent items for send as messages, do the following:
- Open up user properties, select the Mailbox tab, and click Mailbox Delegation.
- Select/de-select Save a copy of Send As messages to Sent Items.
- Click OK twice to apply the settings.