What is the ruling on the *mahr* when separation is due to the husband's action or a third party?

Primary text

If the separation is due to the husband, such as his divorce, *khul'* (redemption), his conversion to Islam, or his apostasy, or if the cause originates from a third party, such as breastfeeding leading to invalidation or an act of intercourse that invalidates the marriage, half of the *mahr* is forfeited, and the other half is due, or *mut'ah* is due to someone other than the one specified for the *mahr*. Furthermore, the husband may seek recourse against the party who caused the dissolution if the dissolution originated from an unrelated third party.