Sorry I wasn't real clear.
If for example a client attaches a pdf I can download it and it will open in acrobat. But if a client uploads an ai (illustrator) psd (photoshop) or eps for example it appears in the folder with the correct extension but will only open in text edit as binary - then I have to save it as whatever format it is supposed to be before it will open in the correct program.
My email client is mail