I am struggling with technician auto assign.

 I created a sub-group with two technician in it. i created a business rule for email mode to be assigned to the subgroup(two the two technicians turn by turn). I added the site of the technicians to  Enable Exceptions to exclude them from  Technician Auto Assign . 

My problem here is, case coming from requesters still go to the two technicians and if the technicians are in " Exclude following technicians" then the case coming through email mode become UnAssigned. So how can i set the SDP to assign automatically to the technicians (the technicians taking turns) and exclude them from any other requests?

Thank you all for your help

Best regards