In this tutorial, I go through how you can send students emails in bulk to all students enrolled in a course using the Groundhogg tool along with the LifterLMS + Groundhogg integration:

https://wpcourseguide.com/go/Groundhogg-LifterLMS

That allows you to spot when someone enrolls in a course in LifterLMS and tag them in Groundhogg to eventually send out blast emails whenever you’re ready.