Problems with setting up Personal ToDo lists on rt 3.6.3

I am trying to setup Personal ToDo lists as mentioned in the O’Reilly
book p. 113 + 114

One of the aims is to make sure the staff can’t see each others ToDo items.

Queue name: TODO

ACLs for priviledged users on the queue

SeeQueue
CreateTicket
OwnTicket

ACLs for the Owner

CommentOnTicket
ShowTicket
ShowTicketComments
ReplyToTickets
ModifyTicket

The problem appears to be that everybody can see the items if they got
created by email. Only after the requestor has gone to the website and
‘taken’ the item will it disappear from the others lists.

A couple questions, how would I write a scrip to assign the ‘Owner’
value to the user associated with the staff emails sender address?

So if jim@domain.net sends to rt-todo@domain.net I would like the
‘Owner’ for that ticket to be set to user ‘tim’, right there at ticket
creation time. How do I do such a thing?

Thanks for any pointers.

Urs Rau