I can save any string without any problem using file_put_contents. But as soon as there's an '@' in the string the script starts an unintented download. The string is sent in a form using the post-method. The php-script contains the following line:
file_put_contents("users/testguy/email.pfl", $_POST['email']);
I expect the string (an ordinary email-address like abc@defghi.xyz) to be saved in the file "email.pfl" ('.pfl' is my alternative to '.inc' and is supposed to be short for 'profile'). But instead a pop-up window in firefox browser asks me how I wanted to proceed with that file (it says: 'Type: application/x-httpd-php'). I have absolutely no idea how this problem occurs. Again: It works flawlessly with any other string.