One of the Misvot that apply on Purim is Mishlo'ah Manot, sending food packages to one's fellow. Megilat Ester (9:19) refers to this Misva with the expression "Mishlo'ah Manot Ish Le're'ehu" "Sending packages one to another" indicating that one must send at least two food items to at least one individual.
The great Kabbalist Rabbi Gamliel Ha'kohen Rabinowitz, in his work Tiv Ha'Purim, suggests a novel explanation for the reason underlying the Misva of Mishlo'ah Manot. The Gemara (Pesahim 6) and Shulhan Aruch (Orah Haim 429) establish the obligation to begin studying the laws of Pesah thirty days before the holiday, in preparation for its observance. Thirty days before Pesah, of course, is Purim, and thus on Purim one should begin studying in preparation for Pesah.
According to Rabbi Rabinowitz, the obligation of Mishlo'ah Manot is part of the Pesah preparations that begin on Purim. Some people observe the stringency not to eat in anybody else's home during the holiday of Pesah. Since many complex laws apply to food preparation on Pesah, these people make a point of eating only their own food, rather than having to rely on the standards of other people. While this is an admirable practice that reflects a heightened sense of Yir'at Shamayim (fear of God), it also runs the risk of causing strife and discord among Jews. The Talmud (Sanhedrin 103) observes that people draw close to one another by eating together ("Gedola Legima She'mekarevet"). The converse of this rule is that by refraining from eating with others, one becomes distant from them. Certainly by refusing an invitation, a person might offend his fellow and cause resentment and ill-will, even though his intentions are purely for the sake of Torah observance.
For this reason, Rav Rabinowitz suggests, we are required to send each other food packages on Purim one month before the onset of Pesah. As we begin to prepare for Pesah and anticipate the possible strife that might arise from the refusal to eat in each other's homes, we neutralize this effect by exchanging gifts of food, demonstrating our mutual love and affection. Mishlo'ah Manot conveys the message that we indeed feel a deep sense of camaraderie with our fellow Jews, and it is only due to our strict devotion to the laws of Pesach that some people do not eat in other people's homes on that holiday.
The obligation of Mishlo'ah Manot is introduced in the Megila together with the Misva of Matanot La'evyonim gifts to the poor: "Mishlo'ah Manot Ish Le're'ehu U'matanot La'evyonim." Some Rabbis noted that the first letters of the words "Ish Le're'ehu U'matanot La'evyonim" spell the word "Elul" the name of the month that immediately precedes Rosh Hashanah. During this month, of course, we increase our observance of Misvot generally, paying particular attention to the Misvot governing interpersonal relations. For this reason, the name "Elul" alludes to the obligations of Mishlo'ach Manot and Matanot La'evyonim on Purim, Misvot which embody the notion of brotherly love among Jews. By the same token, this association indicates that on Purim, too, we must make an extra effort to bridge the gaps and live in peace, harmony and love with our fellow Jews just as we make such an effort during Elul. Purim, like Elul, is a time to strive towards greater unity among the Jewish people, and to refrain from arguments and strife that threaten to undermine our mutual sense of brotherhood.
Purim day is a busy and hectic time, with lots to do and large crowds in the synagogue. The tumult that often characterizes the Purim celebration occasionally causes some tension and discord between people. We must recognize that fighting with other Jews runs in direct contrast with one of the principal themes of this holiday, which is intended to bring Jews together and lead us to a greater sense of unity, friendship and mutual concern.