When you add folks to your Cerkl, they automatically receive a lovely on-boarding or "welcome" email. The subject line of this email reads, "Let's Get Personal" and invites your subscribers to personalize your Cerkl newsletter. They select categories that they want to hear more and less about, their ideal send time and frequency, and desired newsletter format.
Once they complete this quick process, they are officially on-boarded. Subscribers who haven't personalized will still receive your newsletters, they'll just receive them at your organization's default time, frequency, and in your layout as opposed to a personalized format.