Men advising women

Q 6: There was a Muslim girl with us in the school who was a Mutabarrijah (a woman who makes a public display of her charms or adornment). She used to go to nightclubs and sit with European men. I did not have the courage to talk to her directly, but I sent her a letter in which I drew her attention to her adornment, reminded her of some Ayahs (Qur'anic verses) and Hadiths, and enclosed the booklet entitled "Social Fatwas" which includes your Fatwas (legal opinions issued by a qualified Muslim scholar) concerning women's Tabarruj (woman’s public display of her adornment or charms) and traveling abroad.My question is whether what I did was permissible, as she is stranger to me.

A: If you see a Muslim violating Shari`ah (Islamic law), you should advise them and give them useful books to read, as this is considered a form of cooperation in righteousness and piety. Your advice to this girl is Wajib (obligatory) on you, and you will be rewarded for it in Shaa' Allah (if Allah wills). May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.