How to create ticket without log in using CommandBy MAil

[vahid Khorasani]

Hi
I' m working on a project to let lots of external users to create 
tickets anytime the deal with a problem and my support team start 
working on it to solve it ,but I don't have any user accounts for them 
neither in my RT local database nor in my LDAP ( and absolutely I don't 
wanna have any ;-) ).
I installed CommandByMail extension on my RT and I also enabled it in my 
RT_SiteConfig.pm file but it doesn't work.
I have two questions:
1-To whom these external users must send their mail (I mean what email 
address)??
2-Should I add anything special in my RT_SiteConfig.pm ??