This infusionsoft issue suggests that you cant post to the form URL directly “but it will accept forms that have the registered id’s that are a match in the database for that form. ie, their servers have the values of those “inf_form_xid” and will only accept information from that form”.
Essentially, this is what I have done by modifying the unstyled HTML to match my sites theme, and when I leave the action as the infusionsoft URL instead of a custom function, it works. I still see the multiple “too many redirects” console messages though, before it redirects my page to the success landing page.
How can I hook into the form submit to handle the form validation before the POST to infusionsoft (or cancel the POST entirely)?