Save sent email in second account not default account?


Outlook version
Outlook 2010 32 bit
Email Account
Exchange Server

Using Exchange 2010 and Outlook 2010.

We have a shared email account which is accessibly by more than one user. This shared account has been added as an additional mailbox in Outlook, and the users have been given Full Access and Send permissions in Exchange.

When they reply to an email that has been sent to (and is in the inbox of) the shared email account, the users can choose to send the email as having been sent by the shared account (that works fine) but the email is then added to the Sent folder of the user's default email account.

What do we have to setup to get the sent email to remain in/be added to the Sent folder of the Shared email account?? (so that all users with access to the shared email account can view all the messages sent by the other users).