(concurring, with whom Botsford and Duffly, JJ., join). I concur with the court’s opinion but write separately to explain my understanding of the practical consequence of this opinion where mortgage borrowers claim a violation of G. L. c. 244, § 35A, inserted by St. 2007, c. 206, § 11. I do so with the recognition that many mortgage borrowers who will claim such violations will not have the benefit of legal representation, and that our jurisprudence in this area of law is difficult for even attorneys to understand.
*432As the court notes, see ante at note 4, where a homeowner who is facing foreclosure claims that the mortgage holder has failed to provide timely and adequate written notice of the right to cure the default in payment of the mortgage, in violation of § 3 5A, the homeowner may file an equitable action in Superior Court seeking to enjoin the foreclosure. Because, under § 35A (b), the mortgage holder “shall not accelerate maturity of the unpaid balance of [the] mortgage obligation or otherwise enforce the mortgage because of a default consisting of the mortgagor’s failure to make any such payment” until the required time period has elapsed after the required written notice has been provided to the mortgagor by the mortgage holder, the foreclosure may not proceed if the mortgagor proves that the mortgage holder has failed to give the required notice or failed to wait the required time period. If the mortgagor proves a violation of § 3 5A, the mortgage holder must provide the proper notice required by § 35A and wait to see if the borrower will cure the default within the required time period before recommencing the foreclosure proceeding.
Where the homeowner does not challenge the mortgage foreclosure in court, and finds herself a defendant in a summary process action that seeks to evict her from the foreclosed home she continues to occupy, she may assert a defense or counterclaim in Housing Court challenging whether the bank or other party that purchased the property at the foreclosure auction lawfully holds title to the property. See Bank of Am., N.A. v. Rosa, 466 Mass. 613, 621-625 (2013); Bank of N.Y. v. Bailey, 460 Mass. 327, 332-333 (2011). Where a defendant in the summary process action claims that the mortgage holder failed strictly to adhere to the requirements under the statutory power of sale set forth in G. L. c. 183, § 21, and the related requirements in G. L. c. 244, §§ 11-17C, proof of any violation of these requirements will void the foreclosure sale and, therefore, defeat the eviction. See U.S. Bank Nat’l Ass’n v. Ibanez, 458 Mass. 637, 646 (2011), quoting Moore v. Dick, 187 Mass. 207, 211 (1905) (“we adhere to the familiar rule that ‘one who sells under a power [of sale] must follow strictly its terms. If he fails to do so there is no valid execution of the power, and the sale is wholly void’ ”). However, where a defendant in the summary *433process action claims a violation of the requirements in § 35A to provide timely and adequate written notice of the right to cure the default, the defendant must prove more than a mere violation of § 35A to defeat the eviction because, as the court notes, § 35A “is not one of the statutes ‘relating to the foreclosure of mortgages by the exercise of a power of sale.’ ” Ante at 431, quoting G. L. c. 183, § 21. Rather, to defeat the eviction, the defendant must prove that the violation of § 35A rendered the foreclosure so fundamentally unfair that she is entitled to affirmative equitable relief, specifically the setting aside of the foreclosure sale “for reasons other than failure to comply strictly with the power of sale provided in the mortgage.” Bank of Am., N.A. v. Rosa, supra at 624.