Every person must send two gifts of food to a friend on Purim, in order to increase love between them. Increasing love between Jews is part of the essence of Purim, as it was on Purim that the Jewish people’s holiness was revealed. This holiness is expressed in the fact that they cling to God and His Torah, and a spark of this holiness exists in every Jew. Therefore, it is proper to actively express the love between Jews on Purim (see above, section 2).
These gifts must consist of food items in order to enhance the joy of Purim, as it is known that when a person eats good, tasty foods that he received from a friend, the love between them becomes strengthened. Another reason for mishlo’aĥ manot is that some people are not actually poor – they have the ability to purchase basic provisions for the Purim meal – yet are unable to buy foods for a more respectable Purim meal. By sending mishlo’aĥ manot, we can provide them with good food for the Purim meal in an honorable fashion.
The law is that one discharges his obligation by sending two portions of food to one person. The Sages enacted that one must send at least two portions so that the gift will be an expression of love. After all, a single portion of food can help a friend avoid hunger, but when one sends two portions, it means that he wants his friend to enjoy a variety of foods as well. One who gives more mishloĥei manot in order to increase feelings of love, brotherhood, peace, and friendship between oneself and one’s friends is praiseworthy.
Responsa Binyan Tziyon §44 states that, le-khatĥila, one should send mishlo’aĥ manot via a shali’aĥ (proxy), but many poskim do not mention this. Rema 695:4 writes that if one sends mishlo’aĥ manot to his friend and the friend refuses to accept it, one nevertheless fulfills his obligation, as he has still expressed his love just by sending the mishlo’aĥ manot. However, Pri Ĥadash and Ĥatam Sofer disagree. Most Aĥaronim are stringent on the matter.