You can change the destination of any virtmap that exists on your server. To rename a virtmap, however, you must create a new virtmap with the same destination as the original virtmap.
To modify an existing virtmap, follow the steps below:
Click the Virtual User Mappings link from within the Mail Management Menu.
A list of currently defined virtmaps appears, if any.
Click the Edit link next to the name of the virtmap you wish to edit.
The name of the virtmap appears, along with the current destination.
Type the new destination in the text box and click Update.
Click the Restart Sendmail link to activate the changes to your virtmap settings.
An updated list of your current virtmaps appears.