CHICAGO, Oct 15 (Reuters) - Chicago Mercantile Exchange lumber futures again fell for sharp losses Monday and posted new contract lows on selling prompted by a weakening cash lumber market, traders said. Lumber closed $5.70 to $10.00 per thousand board feet lower with November off $5.80 at $219.50 after setting a new contract low of $218.20 per tbf. January ended $5.70 lower at $238.80 after setting a new contract low of $235.50 per tbf. Thinly traded May finished limit down. "Cash is falling and futures are just going down along with it," said one trader citing a light volume decline in futures. Traders noted that private reports put cash spruce in the $210.00 per tbf area early Monday. That is down from Friday's official Random Lengths cash lumber report quoting cash spruce at $226.00 per tbf, down $8.00 from midweek and down $10.00 from week-ago levels. Traders viewed the U.S. Commerce Department's decision to delay whether to impose anti-dumping duties on Canadian softwood lumber until Oct. 30 as negative. The trade had been looking for the additional duty, which would make it hard for Canadian mills to ship wood and would tighten supplies and raise lumber prices in the U.S. Short covering by traders who sold last week provided the only scale-down support, pit sources added.