No notice of dishonour is necessary:

when it is dispensed with by the party entitled thereto;
in order to charge the drawer when he has countermanded payment;
when the party charged could not suffer damage for want of notice;
when the party entitled to notice cannot after due search be found; or the party bound to give notice is, for any other reason, unable without any fault of his own to give it;
to charge the drawers, when the acceptor is also a drawer;
in the case of a promissory note which is not negotiable;
when the party entitled to notice, knowing the facts,promises unconditionally to pay the amount due on the instrument.