For any one that needs this info on opening attachments using FMP! i got this back from form maker pro guys.

We would like to inform you that you can access your uploaded file on your FTP
server in folder "attachments" in your Form Maker Pro directory. You need to
delete "_._file" from the end of the filename. (this extension adding
automatically for the secure reasons, so nobody is unable to upload harmful
script to your server and execute it)

So, by the sound of it! it may be beter to leave as is. & recive the attachment via your email.

Cheers.