SO28 - Starting a workflow when external mail is received

[Lisa Hasenbohler]

I am trying to setup a workflow that will start whenever an external
e-mail is received by a specific user and I need a deeper understanding
of transaction SO28.
 
So far I have
    - created a workflow "WS924000015", it currently has no triggering
event, it needs to receive the external e-mail.
    - created a the following entry via tcode SO28.
                 Recipient:  lhasenbo at zzzz.com  (address that the
external e-mail is sent to)
                 AddrType: Internet
                 New recipient: Handler for messages to work items
(WI_MAILREC)
                 AddrType: Business Object
 
What I don't understand, is how the system would know which workflow
should be kicked off as I have not specified that anywhere?
 
I got the idea to use this configuration from Alan Rickayzen's,
tutorial "A Beginner's Guide to Building Workflows with the Workflow
Builder" and from the book Practical Workflow for SAP-Tips & Tricks-pg
464.
 
The tutorial shows the entry that needs to be made via SO28.  Is there
more to it than that?
 
The book suggests to create your own object that contains "IFRECIEVE"
and "IFFIND", and a "RECEIVE" method that would create a terminating
event, however, as soon as you reference "IFRECEIVE" you are given the
"RECEIVE" method.  Should I create a different method than "RECEIVE",
but how does the system know to run that method?
 
I need some help to further understand how this works.
 
Thanks,
Lisa Hasenbohler
4.6C