[Exim] Mapping email addresses to mailboxes

Hi,

I am pretty sure this is covered in the online FAQ's and
documentation, but I have not found it.

For those of you who are familiar with Sendmail, the sendmail
facility that did exactly what I am looking to do was
the /etc/mail/virtusertable fileset. (for later versions of
sendmail)

I am looking to find a way to map email addresses to mail folders.
This way, I can have bob@??? and bob@??? pointing
to different user accounts, with different passwords and mail folders.

How do I achieve this with Exim-3.13-1 ?

Regards, Jason