Just another thought !!!
You could enable the Send to Self option, This way they get the scan sent to themself, then from their own mail box they forward to whom they want.
Since I work in a very secure site, we did it this way so users don't send the information to the wrong person.
If you want to enable the "Scan to Self" option, you can go to Services -> Email -> Setup -> Security tab -> Heading User Policies -> Click "Edit" by "Send to Self"