I recently ran into an issue where Outlook would not save the email sent on behalf of a shared mailbox into the Sent Items folder of that shared mailbox.
This was causing a problem, as the shared mailbox was set up for sharing between multiple users, and the Sent Items folder was not consistent within each user’s Outlook.
I found a registry edit that solved this problem. On each computer configured with the shared mailbox:
- Close Outlook
- Open the registry and perform a full backup
- Browse to: HKEY_CURRENT_USER\Software\Microsoft\Office\[version]\Outlook\Preferences
- Add a DWORD labeled as: DelegateSentItemsStyle
- Set the DWORD value to 1
- Exit the registry
You should now be OK to open Outlook, and test sending an email through the shared mailbox, as the sent email should now be saved in the Sent Items of the shared mailbox.