How to create business rules to route incidents based on attachment = True or False

Summary

How to create business rules to route incidents based on attachment = True or False

Content

Hi,

We have requirement that, if customer emails comes with attachments (which are customer orders), the incident created should be routed to Orders queue and if there is no attachment then incident should be routed to Enquiry queue.

I tried to check email header, thread etc but couldnt find anything which mentions attachment.

Can you please suggest how if condition should be designed in this case?

Thanks,

Meena