I got tired of maintaining 4 versions so I just put a link on 3 of the sites contact forms to one site.
I have been trying to instead get the other 3 sites to use the same form processing from inside an iframe. I validate $_SERVER['HTTP_REFERER'], though I know it can be spoofed, and have lots of spam checks against hijacking, header injection etc. so I am not too concerned here.
It works sometimes. Other times, when I submit the form, all the values in $_POST just disappear. "Notice: Undefined variable: _POST in ........"
I am so close to having this work the way I would like except that half the time the $_POST array goes away.
Does anyone have any suggestions as to how I could fix this?