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You can't share the entire Slideshow with email. You have to share/export it as a Movie file (Quicktime format) and this will export the slideshow as a movie file (export or save it to desktop, so you can see/open it easily). Now you can send it. If the file is very big, then it won't go through email. In that case, you have to use file sharing or cloud services like Dropbox.
Go to www.dropbox.com
Then create a free account if you don't have one already. This will give you a free 2GB cloud space. Now upload the exported slideshow movie file to Dropbox. After uploading, you will see a Share option in Dropbox. Click it and this will give you the link/web address to download the slideshow. Just share that link/web address with your family and they will be able to download it.
If you have any questions or if you have any difficulty on following the steps above, please let me know and I will continue to help you