When saving a powerpoint file as PDF on Mac the file size is massive and I can't send via email. Compressing the PDF then reduces the quality so much that the quality is too poor to use.
Use A web based service such as Google Drive, iCloud, etc - upload the pptx file to there and then send a link to the person you want to share it with so that they can download it. I do this all the time with large PowerPoint files.