As we have learned, women are obligated in Kriyas Megilah. Nevertheless, a woman should not be motzei a group of men. It is not respectful for a woman to act as a shluchah d’tzibur. She may, however, be motzei other women. Some Rishonim hold that women are only obligated to listen to a Megilah reading but are not obligated to read the Megilah. In their view, even if a woman did read on behalf of a man, he would not be yotzei. Some Achronim say that according to this view, a woman should not read the Megilah to herself. The text of the brocha for a woman is lishmoa mikrah Megilah. Some omit the word mikrah. The poskim disagree about whether one woman may recite the brocha on behalf of other women.
[שו"ע תרפט, ב, ומשנ"ב ז-ח; ביאורים ומוספים דרשו, 26-25]