Contact Form 7 form is working on local wordpress install but fails on production server [closed]

I’ve had this problem before. There’s an easy way and a hard way to fix it.

The easy solution: use a Linux server.

The hard solution: write your own contact form.

IIS 6 doesn’t play nice with anything WordPress uses or does. It works on XAMPP because that’s a LAMP stack running PHP, MySQL, Apache, and (usually, for Windows) Tomcat. When IIS runs those scripts, it’s all going through Windows. Think of your site as fuel, and Windows and Linux as different kinds of engines (diesel and regular. You can decide which you think is which). What works for one doesn’t necessarily work for the other.