The 5T-Far Rockaway community had the privilege of hosting R Asher Weiss on P' Terumah - Shekalim. On Motzei Shabbos he spoke at Shor Yoshuv on the topic of mishloach manos and hilchos Purim. One chiddush to give you a taste: The poskim point out two reasons given for the mitzvah of mishloach manos: 1) The Terumas haDeshen -- to provide food for seudas Purim; 2) The Manos haLevi -- to increase the feeling of brotherhood and camaraderie. The Rama paskens that one is yotzei mishloach manos even if the recipient is mochel or does not accept the mishloach manos. It is widely assumed (quoted in Chasam Sofer) that the Rama is a nafka minah between these two reasons. If the purpose of mishloach manos is to provide food for the seudah, then (lichorah) one has not accomplished anything if the recipient is mochel and not accepted the food. If the reason is to simply engender a sense of brotherhood, then the Rama makes sense -- it's the thought that counts more than the gift.
Rav Weiss thought it unlikely that the Rama really meant to pasken like the Manos haLevi against the Terumas haDeshen. Firstly, the Terumas haDeshen is one of the Rama's most frequently quoted sources for minhag Ashkenaz. Why would the Rama here suddenly abandon the Terumas haDeshen in favor of a Sefardic acharon (the Manos haLevi = R' Shlomo Alkebetz) who wrote his comment in the context of peirush hamikra and not halachic analysis? (R' Weiss even suggested that the Manos haLevi himself may himself have never meant his chiddush l'halacha.) Secondly, the Terumas haDeshen is well grounded in Rishonim. As we noted before, the Rambam places the din of mishloach manos in the context of his discussion of seudas Purim (Hil Megilah 2:16 -- keitzad chovas seudah zu....). Also, when it comes to the dinim of Purim meshulash, the Rishonim all write that mishloach manos is done on the same day that seudas Purim is eaten. There seems to be a strong link between mishloach manos and the seudah.
Therefore, R' Weiss suggested that even the Terumas haDeshen would agree with the din of the Rama. What the Rama meant is simply that Chazal could only make one responsible for sending gifts -- acceptance of delivery is out of a person's hand. You can't make a takanah for a person to do what is out of their hands to accomplish.
The Ksav Sofer discusses whether one is yotzei sending mishloach manos anonymously and suggests the issue hinges on the debate between the Manos haLevi and Terumas haDeshen. If the point of mishloach manos is to ensure someone has food, then the identity of the sender is irrelevant; if the point is to foster camaraderie, then knowing who sent the mishloach manos is critical -- how can you feel friendship with "anonymous" (a lesson for some of you who comment here ; )
Rav Weiss argued that even if one accept the approach of the Manos haLevi, the goal of enhancing comraderie is achieved even with an anonymous mishloach manos. The recipient can feel a closer bond of friendship with everyone, as anyone might be the sender. But in truth, there is no machlokes. The Terumas haDeshen's reason is m'ikar hadin the driving force behind the takanah of mishloach manos. The Manos haLevi is an added consideration, but not a reason to pasel any gift.
(I have omitted many aspects of the shiur, so any errors can be attributed to me, not Rav Weiss.)