AFAIK you canât further compress a zipped or gzipped file. Youâll need to unzip it first. There are plenty of other tools out there to compress PDF files - a search will find them. Whether tâll produce your required compression is something I do not know. On the assumption that the issue is sending relatively large files, there are free utilities to enable that out there. Alternatively it should be possible to split the pdf file, even if that entails turning it into a postscript file as an interim step.
But no, that would be too late, squall have to re-encrypt it first. Note also that the compression is always off — I have never seen any PDF file whose compression is enabled but not the compression method. This is the default in Windows, so Donald expect to see that for Linux. I am aware that there is a command line executable to compress Microsoft PDFs which you can run if your system has the required dependencies. If you are running a Linux system from within Windows itself, however, all the dependencies are not installed, and it is unlikely you could access it, unless you find a work-around that uses a GUI browser. In fact, even for a Microsoft PDF file from a modern OS like Mac OS X, you should not expect to be able to open it — you need to enable compression for that (see above), and it.