I received code written in .NET and Angular and made a change to the registration process. I replaced the existing SMS/Email sending mechanism with a new one that uses an API call. After publishing the app, the site loads correctly, but SMS/email sending fails when running on IIS Local. However, if I run IIS Express in the background from within Visual Studio, the sending works both from the published site and from the local host. As soon as I stop running IIS Express in Visual Studio, SMS and email sending fails again from the published site.