Can my mahr be used to cover the cost of the wedding reception?

Yes, if you yourself are willing, because the mahr is yours to spend as you wish. But do not let anyone automatically treat it as a ‘reception fund’. Think first about whether you want to keep part of it for emergencies or your first home. If you choose to contribute, state the amount clearly to your family and husband. For example: ‘I will put half towards the kenduri; I will keep the rest.’ That way the contribution is appreciated as your gift, not an obligation taken without asking. See a wife waiving her mahr.