Un-opened Email Automatic Warning

As I'm seeing a very low open rate on new prospects, I'm trying to figure out how to boost this. On a LionDesk FAQ I saw the following:

"Unengaged subscribers

Are you continuing to send to users who haven’t opened an email from you in the past month? 3 months? A year or more? Continuing to send to folks who never engage with your email is another strong, negative signal to inbox providers that you, as a sender, are not paying attention to your email list quality. We typically suggest stopping sending to, or at least greatly reducing frequency to, addresses that have not opened an email you’ve sent them in the past 3-6 months. You really, really don’t want to send to addresses that have gone a year without engaging."

It would be a major help if LionDesk could generate a report of all prospects in my database that have not opened an email in 3 months, 6 months or a year. This way I can turn off any campaigns that are falling on deaf ears.