[rt-users] Tryin to disable automatic User creation

[oakcluster]

I would like to disable the automatic creation of users that is done via 
email.
We use RT only for a very select group of people and try to keep it 
tightly controlled. The main reason for this is maintenance. We are not 
staffed to handle
the care and feeding of RT on a large scale and we are only evaluating 
it right now. Still people talk and so we are getting request from 
people that are not in our test groups. Since the groups are small it is 
not impractical to manually add and delete users at this point. So I 
just need a way to turn off that automatic user creation.

I read the RT_Siteconfig.pm and found the following:

   # If $SenderMustExistInExternalDatabase is true, RT will refuse to
   # create non-privileged accounts for unknown users if you are using
   # the "LookupSenderInExternalDatabase" option.
   # Instead, an error message will be mailed and RT will forward the
   # message to $RTOwner.
   #
   # If you are not using $LookupSenderInExternalDatabase, this option
   # has no effect.
   #
   # If you define an AutoRejectRequest template, RT will use this
   # template for the rejection message.

I created an AutoRejectRequest template

and set the following:

    Set($LookupSenderInExternalDatabase, 1);
    Set($SenderMustExistInExternalDatabase , 1);

However I received no rejection notices, just our standard ticket 
creation with username and password information in the email.

I checked the book, Wiki and google. I searched through all of the code 
under /opt/rt3 and found no references
to the variables above (except of course in the config file), leading me 
to believe that this functionality is not implemented.

If anyone knows of anyway to turn off the automatic user creation I 
would appreciate it.
Or if you have suggestion as to where I could implement the code to use 
these parameters, that would be helpful too.

Thank you.