M.G.L. c. 183 § 29 provides that a deed cannot be recorded unless it has been duly acknowledged.  The caselaw appurtenant to § 29 suggests that the failure to acknowledge will render a deed void even if it is recorded, Graves v. Graves, 72 Mass. 391 (1856), Inhabitants of Raynham v. Snow, 53 Mass. 157 (1846).  Also, It should be noted that although acknowledgement is a prerequisite to recordation, a deed's validity is also dependant on effective delivery by the grantor,  Murphy v. Smith, 291 Mass. 93, 195 N.E. 912 (1935), and a concomitant acceptance by grantee, Jucho v. Toton,338 Mass. 309, 155 N.E.2d 162 (1959).

As a caveat, it may be worthwhile to note that although there is no similar statutory requirement of acknowledgement for mortgages, Massachusetts is a "title theory" state Atlantic Savings Bank v. Metropolitan Bank and Trust Co. 9 Mass.App. 286, 400 N.E.2d 1290 (1980). That is, a mortgagee takes title to the realty subject to the mortgagor's rights of redemption, effectively making the mortgage a deed, Atlantic Savings Bank, 9 Mass.App. 286. Query whether the § 29 requirement would therefore apply to mortgages also.

As to discharges, M.G.L. c. 183 § 54C provides in pertinent part that "...[t]he recordation of a discharge duly executed and acknowledged...shall constitute a discharge of the mortgage and a release of the lien created by such mortgage..." (emphasis added).   Here, the necessity to acknowledge is clear and prudent conveyancing would require that a discharge be notarized.  Also, where a discharge is from a corporate entity, M.G.L. c. 183 §54B requires that if such discharge is not accompanied by a corporate resolution, the discharge needs to be acknowledged in order to be recorded, see also, MCA title standard 16.