Technical documents for protocols, computer languages, standards support, and data portability. The goal with Open Specifications is to help developers open new opportunities to interoperate with Windows, SQL, Office, and SharePoint.
Thanks @BillsonBruce-4044, for reporting this. I've reported this and the links should be fixed soon. In the meantime, here is the link to the Exchange Protocols zip file:
https://msopenspecs.azureedge.net/files/Zip_Files/Exchange_Protocols.zip.
Best regards,
Tom Jebo
Microsoft Open Specifications Support