My family is not “officially” Chabad, but we are very close to the Chabad community. My children attend a mixed-school where they serve non-chalav-yisrael milk on the menu and I know how important chalav yisroel is to the Chabad community. I may be in a position of influence in the school. Should I try to push chalav yisroel or should I “save my power” for a different (and possibly more important) issue?

Thank you for this question, it is truly interesting and thought-provoking. Before I share certain letters that the Rebbe wrote on this topic, I would like to preface two important things:

(a) This is not the place to discuss the halachic debate behind the heter of Rabbi Moshe Feisnstein z”l in regards to company-manufactured non-chalav yisroel milk. Suffice it to say that Reb Moshe himself told a school that wanted to use regular such milk to feed their students, that they should only feed them chalav yisroel (אגרות משה יו”ד חלק ב סי’ לה, יו”ד חלק ד סי’ ה).

(b) The question of chalav yisroel is not just a halachic debate; it has deep spiritual consequences. The Frierdiker Rebbe (Sefer Hamamarim Yiddish, pp 57) brings down a story that took place in the time of the Alter Rebbe:

The Long Lasting Effects of Chalav Akum

A person who came with his son-in-law, a great Torah scholar, to the Alter Rebbe in Liozna, and complained that his son-in-law always conducted himself in an appropriate way, but suddenly one day he began having doubts about belief in Hashem and he himself had great agony from this. The Alter Rebbe responded, that the son-in-law had without his awareness eaten from cholov akum and subjects similar to cholov akum – “This originated from the yetzer hara – evil inclination who throws his arrows from a distance and they, G-d forbid, kill or wound the person, in a spiritual sense.”

“Important especially for those that are in mixed schools”

With these introductions in mind, let us see some answers that the Rebbe wrote to individuals that worked hard to bring chalav Yisroel to their communities:

(1) Rebbetzin Shula Shifra Kazen A”H was the pioneering shlucha together with her husband, Rabbi Zalman Kazen A”H – to Cleveland, Ohio. In the early 50s she worked hard to make chalav yisroel available in Cleveland. She merited the following response from the Rebbe:

“I was so happy to receive your letter about your efforts in regards to chalav yisroel … Hashem should help that you should not get weakened in continuing to work on this and then it will surely continue to be successful…This merit (for pioneering chalav yisroel in Cleveland) should stand by you, and all those that are active in this regard, for all that you need physically and spiritually. (Igros, Vol. 12 p. 79; #3888).

(2) Rabbi Yitzchak and Mrs. Reyza Kosofsky A”H, were active members of the Lubavitch Kehilla in Chicago and were completely devoted to the Rebbe’s Mivtzoyim. In the 1960s and ’70s, encouraged by the Rebbe and under the direction of Rabbi Tzvi Hirsch Meisels (the Veitziner Rav), Kosofsky arranged the oversight and production of chalav yisrael milk for Chicago.

In 1962, he received the following answer from the Rebbe: “I am so pleased to hear about your success in making chalav yisroel available in your community. Especially according to the famous story that was told over by our holy Rebbeim that chalav yisrael strengthens the Emunah and chalav akum can cause the weakening of Emunah. (Igros, Vol. 22 p. 132; #8335).

(3) Rabbi Sholom Rivkin A”H was the Chief Rabbi of S. Louis, Missouri. He had a young man in his community whom the Rebbe told to be careful about chalav yisroel. Rabbi Rivkin wrote to the Rebbe about it (it seems from the letter that this was causing some friction between this young man and his parents) and the Rebbe responded:

“What I spoke with him about chalav yisroel is based on the famous story told by the Frierdiker Rebbe that chalav akum brings a person to have spiritual doubts. …If at all times, we were supposed to be careful about this, it is especially important for the American youth and especially those that are in mixed schools… (Igros, Vol. 16 p. 243; #6017).