It seems someone has tried to migrate the mailing list archives from mailman to some new fangle code. This has broken the archives for at least freebsd-numerics@, freebsd-office@, freebsd-net@
As a comparison, simply go to https://lists.freebsd.org/mailman/listinfo and follow the links to freebsd-numerics and freebsd-toolchain. Can this be fixed? -- Steve