Is there a way to segment out subscribers who have not opened an email? This is other than the "Cold Subscribers" feature that you CK has. For example, in MailerLite, the current ESP that I use, i can create a segment from people who *have not* opened my newsletter. Or, i can create a segment from people who *have* opened it. This way, I can send it only to the subscribers who have been engaging with my newsletter for a few weeks (to help my sender reputation), and then try sending it to my subscribers who have not opened.