I seem to be getting open rates of nearly 100% in the first 30 mins of a mass email being sent though Marketo. The template has been used many times over without issue. However the last 3 sends have all had unrealistic open rates within 30 mins. I've checked the code for broken tags to make sure that tracking happens normally and i can't see anything wrong. Does anyone else seem to get this issue? Ive attached the code for reference.