Any setting to invite subs from a prior email service, to our Squarespace email list?

Hi, I have a 5000+ email subscriber list (in csv format) from a prior email service. I don't want to just add them to squarespace. Ideally, I would send all 5000 an invite to subscribe aka opt-in, directly from Squarespace. I haven't found this option in settings. Am I missing it, or is not a current feature?