User's Guide
Address Book
Registering a frequently used destination on this machine will save you the trouble of having to enter it each time you send data. A destination registered on this machine is called an "Address Book".
You can register up to 2000 one-touch destinations in the address book. The destination types that can be registered are E-mail address, computer name, etc. depending on the transmission mode.
Select whether to allow the user to register or change destinations (default: [Allow]). For details, refer to Here.