i love your php formmail since the first days. unfortunately, it always got more complex. i did a little hack, regarding referers and recipient domains. you won't have to edit the formmail anymore, you don't have to add the recipient domain to referers and you can forget the www. within the referers.
changes: decodes_vars moved to the top.
then use this to make your life easier:
$form = decode_vars();
hope you like it. if you decide to use it, please put a little link to my hp.
btw: i loved the possibility of giving different answers in the html output, as it was offered in earlier versions. could you implement it again? i already did :-)