In a conveyance of real estate the words “special warranty covenants” shall have the full force, meaning and effect of the following words: “the grantor for himself, his heirs, executors, administrators and successors, covenants with the grantee, his heirs, successors and assigns that the granted premises are free from all enucumbrances [encumbrances] made by the grantor, and that he will, and his heirs, executors, administrators and successors shall warrant and defend the same to the grantee and his heirs, successors and assigns forever against the lawful claims and demands of all persons claiming by, through or under the grantor, but against none other.”