Is defamation included in the second category, for which the forgiveness of the one wronged is not required?

Slander entails a right for the created being, and the slandered person must be sought for forgiveness, in addition to the conditions of repentance. If the slandered person has not been informed of the slander, and one fears causing harm by informing them, it is sufficient for one to supplicate to Allah for them, and to speak well of them in the places where one spoke ill of them, and to recant one's own words.