Hakim al-Umma Mawlana Ashraf Ali Thanawi (Allah ahve mercy on him) said regarding this,
The first type of gathering is that which does not contain any of the prevalent and customary restrictions (quyud). Neither [does it contain] mubah (permissible) restrictions nor makruh (prohibitively disliked) ones, i.e., it is free from all [sorts of] restrictions. For instance, a few people gathered by coincidence, no one had invited them with any extraordinary effort; rather they were gathered for some other permissible event. In this gathering, either by reading from a book or by delivering a lecture, the blessed event of the birth and the characteristics, habits, miracles and virtues of our Radiant Master (Allah bless him and give him peace), the Lord of the Universe, the Source of Pride for the Prophet Adam (may Allah’s peace be upon him), were narrated based on sound sources.
During this narration, if the need was felt to enjoin good actions and discuss religious rulings and one proceeded in doing so without hesitation or this gathering was held to listen to a religious discourse and within it these blessed events and virtues were narrated, then this is the type [of mawlid] that is permissible without any objection. Moreover, it is sunnah and mustahabb (recommended).
The Honorable Prophet (Allah bless him and give him peace) narrated his personal events and virtues in a similar way and later his Companions (may Allah be pleased with them) narrated them, the chain of which continues through the hadith scholars of present with the blessings of Allah Most High and it will continue until the end of time.