How to activate randomized filenames in powermail

i have a form where user could upload files. There are 3 files they could upload and each of them need to have an unique name. So even the person upload the same file everytime i neet different names for it in the email, i get from the form.

So i try to use randomizeFileName. https://github.com/einpraegsam/powermail/blob/develop/Configuration/TypoScript/Main/setup.txt#L538

Cause i dont have the randomizeFilename in my constants.txt it try to enter it in my setup.txt with a real value.

# File upload settings
            file {
                folder = {$plugin.tx_powermail.settings.misc.uploadFolder}
                size = {$plugin.tx_powermail.settings.misc.uploadSize}
                extension = {$plugin.tx_powermail.settings.misc.uploadFileExtensions}
                                    randomizeFileName = 1
            }

But sadly that dont work. The file issues-1.pdf still has the same name (+ a suffix cause i tried it a lot time )

I hope someone can help me. Thank you very much!