menu item call from tpl file
The right way to do this if you are using a Drupal module is to set up a form using the Form API and process things within the context of a module. You can also use a contributed module such as Webform to accomplish this too, but if you want something really custom, you should not just create a form in a template file.

All of this said, make sure your "action" is set to the same path as your menu item and that after you have created your hook_menu entry you clear the cache, so your menu item becomes part of Drupal's menu registry.