The Most Recent Archives Off the Mirrors
The recent-version-off-a-mirror system has no info about your requested package "win64-ssl-sspi"! :-( This is most likely because there is no up-to-date release for "win64-ssl-sspi".
This service automatically and frequently scans through known mirrors and builds links to the latest versions of many different curl archives. This page is fine to bookmark! The above Metalink lets you download this file faster by downloading from several of these mirrors simultaneously, using the appropriate software.
Verification of PackagesThe script that "verifies" mirrored files only checks if they are present or not, to verify that you can download them.
To be really sure that the contents of the files are correct, you should use the checksums and GPG signature to verify downloads!