Stop Automatic Lead Email
I found a hack solution which I hope someone can improve.
Basically the email comes in and adds an entry to the table mail_message.  The type is set as "email" and this seems to be the issue.  If I change it to "notification", the original email does not get sent to the newly assigned salesperson which is the behaviour that I want.
Create a server action on the incoming email server that executes the following python code:

cr.execute("UPDATE mail_message SET type = 'notification' WHERE model = 'crm.lead' AND res_id = %s AND type = 'email' ", (object.id, ))
We are using OpenERP 7 to manage leads within our organisation.  
Leads are created by incoming emails.  When assigning to a different sales person, the sales person gets an email with the original email and the from address is the original person that emailed it.
This is a problem because it looks like the customer emailed them directly and encourages the sales person to manage the lead from their email, rather than sending responses from the OpenERP system.  How can I stop this email from being sent?   I want to make my own template and use an automatic action to send a notification.
There is no automatic action sending this email.  I believe it is somewhere in the python code.