Does a handwritten letter from plaintiff to defendant provide notice of a failure to obtain insurance and/or a cure?

Defendant contends this notice is legally insufficient pursuant to Siegel v. Kentucky Fried Chicken, 108 AD2d 218, 220 (2d Dept. 1985), aff'd 67 NY2d 792 (1986). Plaintiff not only disagrees on the law, but points to the two prior handwritten letters from plaintiff to defendant as giving notice of the alleged defaults. The letters stated the nature of the defaults and demanded a cure, although only one letter included the failure to obtain insurance. In the first letter, plaintiff advises defendant that if there is no timely cure, it will retain counsel to commence foreclosure.