Formstack automatically collects the IP addresses of users submitting forms. You can find this info on the Submissions tab of your form by clicking on each individual submission.
In some instances, you may want to insert these IP addresses into a Notification or Confirmation email. While setting up your email, you'll want to select the custom message option and then you can locate the IP option under the Form Field Panels "Extras" section. From there, you can drag and drop the IP Address variable into the custom message. The variable will be replaced with the IP address of the person submitting your form on the email itself.
Note: If you're interested in learning more about setting up a notification or confirmation email, check out this article.
Note: You can also insert variable code, including the IP Address into the Subject Line of the Notification or Confirmation email by dragging and dropping it.