Follow the steps below to build a signup form for a static list:
Create a standard list by navigating to Audience > Lists and clicking Import List. For more information, read Importing User Lists.
Once you have a list for which you'd like to create a signup form, return to Audience > Lists. Hover over the list and click on Signup Form.
Use the sample code to build your form.
If a user submits an invalid email address using the form code shown above, they will be redirected to an Iterable error page. To avoid this, edit the form code to add validation logic.