I have a population I want to send an email to, but only to those members who have opened an email in the past year. Measures seem to only look back 6-months, and don't seem to return accurate data when I've tried using them.

Is there any way to determine openers over a longer time frame? Can I query for this? This is such an easy function in every other ESP I've used. Not sure why I'm finding it so difficult in Marketing Cloud.