That error is not coming from your code snippet, correct? Is it coming from winzip (or some other extraction program) when you try to extract it? I wonder if your extraction program is barfing because it doesn't know how to handle the decompression. If you're going to compress the archive, you should name it either newpart.tar.gz or newpart.tgz. Then your extraction program may be better able to handle it or at least you've let others know the archive needs to be unzipped first. And if your mailing compressed, I wouldn't use the application/tar mime type, application/x-gtar would probably work better.