Help creating exim service filter

I am looking to create a filter on exim so that if the username sending equals user@domain.com and the email contains an attachment, then send, but if it doesn"t, don"t send it. One of our customers has an NVR that sends email alerts when it detects motion. The problem is it sends 3 emails - one saying alert opened, one with the alert and a picture, and one saying alert closed. We got one of our IPs blacklisted by google because they had company over and it sent 30 emails instead of 10 in one hour. It will always send using the same email to a specific recipient so if sender equals X and receiver equals Y, I need to filter it so that if there"s no attachment (the image), just discard the email. How can this be done? I found this page from docs but I don"t know the syntax to use: