Section 6D. Every mortgage and assignment of mortgage secured by residential property, as defined in section 1 of chapter 255E, presented for record, in which a mortgage broker, as defined in said section 1 of said chapter 255E, is involved shall contain or have endorsed upon it the name, post office address and license number of the mortgage broker and, if applicable, the mortgage loan originator, as defined in section 1 of chapter 255F, responsible for placing the mortgage loan with the mortgagee. This endorsement, or notation that no mortgage broker or mortgage loan originator was involved in the mortgage, if known, shall be recorded as part of the mortgage or assignment of mortgage. Failure to comply with this section shall not affect the validity of any mortgage or the recording of any mortgage or assignment of mortgage.