The cellspacing attribute will no longer be rendered on the <table> tag if it has it's default value (1px) and Application Styling has been enabled. You should apply equivalent CSS styling to set the border-spacing instead.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2