May a woman write a Megillah?
Some Poskim rule a woman is valid to write a Megillah, and one may thus even initially read and fulfill the Mitzvah from a Megillah written by a woman. Other Poskim, however, rule a woman is invalid to write a Megillah, and thus one who reads from it does not fulfil the Mitzvah even Bedieved. [Practically, the widespread custom is like the latter opinion for women not to write Megillas for reading purposes and even if such a Megillah was written, one is not to initially use the Megillah to fulfill the Mitzvah of Megillah reading. However, in a time of need such as when there is no other Megillah is available, one may read from it without a blessing. Even in such a case, if another Megillah written by a man later becomes available, one is to read from it again without a blessing.]
 See Shaareiy Teshuvah 691:1; Kol Yaakov 691:6; See Admur 39:1 regarding Tefillin; Sdei Chemed Asifas Dinim Purim 12; Nitei Gavriel 30:1
 Birkeiy Yosef 691:6 based on Peri Chadash 691:3 and Mateh Yehuda 691:2 who validate writing with left hand, brought in Shaareiy Teshuvah and Kaf Hachaim ibid; Machazik Bracha 691:2; Beis Oveid 6, p. 169b; P”M 691 M”Z 2; Nishal David 12
 The reason: As women are obligated in the Mitzvah of Kerias Megillah and there is thus no reason to invalidate them from writing it. [Chida ibid; Beis Oved ibid; P”M ibid] Furthermore, the Megillah itself states that Esther wrote it, from which various Halachos are derived as explained in Megillah 19a!
 Maaseh Rokeiach on Rambam Megillah 1; Mileches Shamayim Hilchos Stam 24:3; Rav Akiva Eiger 691:2 “It seems that if a woman wrote the Megillah then it is invalid, just as we rule regarding Tefillin and Mezuzah”; Avnei Nezer O.C. 516:19 “If only all our Torah would be as clear as the ruling here that women are invalid to write a Megillah”; Mikraeiy Kodesh 33
 The reason: As women are invalid to write any Stam [scribal writing], even if they are obligated in the Mitzvah, as ruled regarding Mezuzah and Sefer Torah. [Rebbe Akiva Eiger ibid; See Michaber Y.D. 281:3]
 See Shaareiy Teshuvah and Kol Yaakov ibid
 Shaareiy Teshuvah and Kol Yaakov ibid