This is a letter to the tenant that tells the tenant to vacate the property within 10 days or come into compliance with the landlord's requests. An obvious circumstance for when a 10-Day notice is permitted is when the landlord has not received rent payment from the tenant.
Under federal law, the servicer must generally send you a payoff statement within seven business days of your request, subject to a few exceptions. (12 C.F.R. § 1026.36.)