Mass. Gen. Laws ch. 106, § 1-308: Performance Or Acceptance Under Reservation Of Rights

Section 1–308. (a) A party that, with explicit reservation of rights, performs or promises performance or assents to performance in a manner demanded or offered by the other party does not thereby prejudice the rights reserved. Such words as ''without prejudice'', ''under protest'' or the like are sufficient.

(b) Subsection (a) does not apply to an accord and satisfaction.