Googling does not give simple examples and it's giving me a headache trying to figure out IIS 6.0, ASP.Net, HTML, Forms, Post Method Verb, AND PHP all mixed together. My suggestion is to just customize your HTTP 405 Error page as it is the default result for POST attempts. Is SO much easier as this only took me 2 minutes of web design for 405 and that was back in 2009. Today, still no google result seems to help. Trust me, 405 is easier than years of headache. 🤬