Allow 'Email Inbox' feature to be used for leavers

The Email Inbox feature is incredibly useful to quickly upload emails to employee documents and I use it all the time. However where it falls short is not allowing us to send emails as documents when the employee has left.

The employee is still there in the system, just as a leaver, so it would be great to be able to continue sending emails as documents for them to record things like employment references or any queries, issues or other general emails after they leave.