Mishloach Manot -- Sending Gifts on Purim
Darche Noam Source Guide
Section 2 -- The theory behind practical halakhic questions

Mishloach Manot Source Guide Section 1 (main page)

Practical Ramifications of the Different Reasons quoted for sending Mishloach Manot:

Issue	Terumat Hadeshen 111: Mishloach Manot insures that everyone will have a proper festive Purim meal.	Manot Halevi: Mishloach Manot increases friendship and unity.
sending non-food items	does not fulfill the mitzva -- this is the original question the Terumat Hadeshen commented on	does fulfill the mitzva -- increases friendship. In fact, the Manot Halevi was a book originally given as Mishloach Manot(!)
the recipient refuses the gifts	does not fulfill the mitzva	does fulfill the mitzva -- the giver has shown his friendship (See Rema at the end of OC 695, Pri Chadash argues -- see MB 24))
when to send them during Purim Meshulash (when Shushan Purim falls out on Shabbat)	on Sunday when the Purim meal is	Perhaps on Shabbat itself, the actual day of Purim
sending a rich person something beneath his status	does not fulfill the mitzva -- he won't use it for his meal (Biur Halakha, quoting Chayei Adam and Ritva)	does fulfill the mitzva
sending a milk dish to one eating meat in his Purim seuda	does not fulfill the mitzva -- apparently. But if he can still give it to others in his household he would.	does fulfill the mitzva
sending anonymously	does fulfill the mitzva	does not fulfill the mitzva (Ktav Sofer 141:4)
a rich person sending something beneath his status	does fulfill the mitzva	does not fulfill the mitzva -- apparently -- an affluent giver sending something below his status would not necessarily show friendship
sending before Purim but it will arrive on Purim	does fulfill the mitzva -- it can still be used at the meal	does not fulfill the mitzva -- maybe -- perhaps the act of giving must be done on Purim (but perhaps because the increase of friendship resulting from the gift happens on Purim he does) (Beir Heiteiv 695:7)
Do both giver and recipient fulfill the mitzva?	apparently not -- the giver does, and the recipient fulfills the mitzva of Seudat Purim	Perhaps both do, for both are part of the increase in friendship. (See Bach on OC 695)

This is definitely not the exclusive way of looking at things; many of the above and below can be looked at differently.
The sources quoted here are not the only ones dealing with these issues; some are the subjects of discussion among a number of acharonim.

The chart below collects a number of instances where the words of the Megilla are quoted as proofs one way or another.
MB stands for Mishneh Berura; all selections are from Orach Chayim 695.

Issue	What might it be dependent on?	Who speaks about it?
need for a messenger	"Mishloach" might imply sending through a messenger (ideal, not necessary)	Binyan Tzion 44 (MB 18)
two types of the same food	"Manot" implies two different portions -- how different must they be?	Rosh Yosef and Arukh Hashulchan 695
must both be given together?	"Manot" might imply that they are sent together	Chida in Kikar Laaden (others argue)
sending unprepared food	unprepared food is also referred to as "Manot" in Tanach, but "Manot" is used in Rabbinic lit. for prepared food	Maharil (Darkhei Moshe 695) others argue
one couple sending to another	Although "Ish l'reieihu" implies a man sending to another man, a husband and wife can be considered as one unit	MB 25
sending to a rav	Can a rav be referred to as "reieihu"? yes	Mahari Assad 204 & others
sending to a child	Can a child be referred to as "reieihu"?	Kaf Hachaim 694:12 -- no vs. Arukh Hashulchan 695:18 -- yes
sending Shemitta produce	Can one fulfill an obligation using Shemitta produce or is it tantamount to paying back a loan? It is best for the first to be non-Shemitta and not to use Shemitta produce for returning Mishloach to one who sent it	Minchat Yitzchak Torah Lishma 153