File Unblock

public static class FileUnblocker
{
    [DllImport("kernel32", CharSet = CharSet.Unicode, SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool DeleteFile(string name);

    public static bool Unblock(string fileName)
    {
        return DeleteFile(fileName + ":Zone.Identifier");
    }
    public static IEnumerable<string> UnblockDirectory(string directoryName, string searchPattern = "*.*")
    {
        foreach (string file in Directory.EnumerateFiles(directoryName, searchPattern, SearchOption.AllDirectories))
        {
            if (Unblock(file))
                yield return file;
        }
    }
}