Issue:

When submitting the form, the browser returns "The requested method POST is not allowed..."

How to solve:

Receiving that message is a very strange behavior from the webserver and the script is not responsible for that error message.

You should contact your webhosting provider in order to know what can be the cause of the error.

Maybe your webserver doesn't supports scripts execution (PHP, ASP or Perl), or it requires a particular directory to execute scripts, like cgi-bin for Perl.