The answer to this question is constantly evolving, with new and conflicting case law addressing specific facts released almost yearly. The old adage of being able to redeem your mortgage (payout your mortgage) during a power of sale proceeding so long as the mortgagee in possession (being the seller) has not yet entered into a firm or unconditional agreement of purchase and sale with a buyer is no longer clear cut.
Today the way I understand it is that there are two issues once the mortgagee in possession (being the seller/mortgage lender) enters into an agreement of purchase and sale with a potential buyer, and whether or not the borrower/mortgagor can still redeem (payout) his mortgage and keep his property:
- Agreement of purchase and sale has conditions that must be satisfied prior to the agreement becoming “firm”; and
- The agreement of purchase and sale includes a redemption out clause that the mortgagee has a right to accept redemption from the mortgagor of the property up until the date of closing, without liability to the buyer or seller. A redemption out clause is a commonly inserted by sellers (mortgagees/lenders in possession conducting the power of sale) into the agreement of purchase and sale, whereby the sellers reserve the right to cancel the agreement of purchase and sale with the buyers at anytime on or prior to closing in order to allow the borrower (mortgagor) the ability to payout the the mortgage debt and save their home from being sold to someone else.
There are a line of cases that support the proposition that pending the satisfaction of the conditions in a conditional agreement, the mortgagor’s right to redeem is still extant. See: Nalisa Investment Ltd. v. National Bank of Canada,  O.J. No. 643 (Ont. S.C.); Canada Permanent Trust Co. v. Rieckenberg,  O.J. No. 930 (Ont. Dist. Ct.); Miranda v. Wong,  O.J. No. 231 (Ont. H.C.J.); Weiss v. Standard Trust Co. (Ont. Gen. Div.), unreported August 5, 1993, Justice Wilson; National Trust Co. v. Saad (1997), 1997 CanLII 12134 (ON SC), 33 O.R. (3d) 419 (Ont. Gen. Div.). The conditions relied on include a redemption out clause, which conflicts with the Court of Appeal in Logozzo v. TD Bank.