In postfix, there is the "virtual" file which contains a simple list of email-addresses and the users they belong to:

```
myname@mydomain.com                       user
my.name@mydomain.com                      user
my_name@mydomain.com                      user
myname@myotherdomain.com                  user2
someone@myotherdomain.com                 user2

```

This basically allows "user" to have more email addresses than just "user@mydomain.com" and it allows to point "myname@mydomain.com" to a different user than "myname@myotherdomain.com".

How can one replicate this behavior in Exim?