Tafsiran Ester 9:19: Rashi & Ralbag Esther

Unwalled. Who do not reside in walled cities, [celebrate] on the fourteenth, and those who reside in walled cities [celebrate] on the fifteenth, like Shushan; and [these cities] must have been surrounded [by walls] since the days Yehoshua Bin Nun. So did our Rabbis expound and learn.⁴Maseches Megillah 2b. Shushan which was without a wall in the time of Yehoshua was accorded special status “because the miracle was performed there.”

That is why village Jews, who live in unwalled towns: Since Shushan was a walled city, they wanted all of the walled cities to follow the custom of Shushan, to remember this miracle that was done there. For the root and the essence [of the conflict] was there, as has been explained in what preceded. Moreover, the greats of the Amalakites and their ministers were there. And that is why they made the fifteenth day of Adar a day of banquets and joy; since they rested from their enemies on it. However the Jews that dwelt in the cities that do not have a wall make the fourteenth day a day of banquets and joy, since that is when they rested from their enemies. And since the cities that were then called unwalled was already made clear in the Book of Joshua, and the decree [of the fourteenth] was extended to every city that was called unwalled, we know that the law of the unwalled cities is only practiced in them. For these are the ones the way of which is to be without a wall. However the law of the remaining cities, the way of which is to be fortified, is not like the unwalled ones regarding this matter, even if they do not have a wall now.

Sending. This מִשְׁלֹחַ is a noun like מִשְׁמָר [guarding]⁵Nechemyah 12:24. and מִשְׁמָע [hearing],⁶Yeshayah 11:3. therefore the shin is vowelized softly [without a dagesh].