I'm wondering if it's possible to create a "double opt-in" to a mailing list group workflow using Caldera Forms CiviCRM integration. Where the user would enter an email address into a field, then gets sent an email with a link they need to click to confirm they want to be added to the mailing list, and on doing so they're added to the appropriate group in CiviCRM. Essentially the same workflow as using a profile to sign up for a mailing list with the "Enable Double Opt-in for Profile..." settings checked.
Yes, one could just use a profile for this (and have in the past) but would prefer not to deal with the added security risk of enabling external form submissions. The mailing list signup form is in a sidebar widget, not a page, so using a shortcode isn't an option that I'm aware of. Even shorcode widget plugins don't seems to work for this purpose.
So, how would we set up a workflow to use Caldera forms to do this? We have it set up now in such a way that the user inputs their email address, and we use the Contact processor to process their email address and add them to a specific group. This works a treat, just want to explore options for the confirmation email step.