It is perfectly Islamic to hold meetings of men and women inside the mosque, whether for prayers or for any other Islamic purpose, without separating them with a curtain, partition, or wall.
Dr. Rif`at Fawzi, former head of the Shari`ah Department, Faculty of Dar Al-`Ulum, states: “It is highly encouraged for women to attend lessons in order to learn religious affairs, since women are charged with the same duties for which men are responsible in many religious matters. There is no harm whether the scholar instructing them is a man or a woman. This practice used to be done by the Prophet (peace and blessings be upon him). In this concern, Imams Al-Bukhari and Muslim have related on the authority of Abu Sa`id Al-Khudri (may Allah be pleased with him) that some women requested the Prophet to fix a day for them, as the men were taking all his time. On that he promised them one day for religious lessons and commandments. Once during such a lesson the Prophet said, “A woman whose three children die will be shielded by them from the Hellfire.” On that a woman asked, “If only two die?” He replied, “Even two (will shield her from the Hellfire).”
In addition, during the occasions in which women attend, such as the `Eid Prayer, the Prophet (peace and blessings be upon him) used to dedicate a sermon for them despite the fact that men were also present. In this connection, Jabir ibn `Abdullah (may Allah be pleased with him) narrated that “on an `eid day the Prophet (peace and blessings be upon him) started with prayer and then delivered the sermon (khutbah). After he had finished the sermon, he went to the women and preached to them while he was leaning on Bilal’s hand. Bilal was spreading his garment and the women were putting alms in it.” Ibn Jurayj (the sub-narrator) said to `Ata’ ibn Abi Rabah who reported the hadith from Jabir, “Do you think it incumbent upon an imam to go to the women and preach to them after finishing the prayer and the sermon?” `Ata’ replied, “No doubt it is incumbent on imams to do so, and why should they not do so?”
In his narration of the abovementioned hadith, `Abdullah ibn `Abbas said, “…the Prophet preached them and ordered them to give charity.”
Commenting on the hadith, Ibn Hajar said, “The imam (ruler) himself or his deputy is recommended to do so (that is, preach to women). In the hadith narrated by Ibn `Abbas, the phrase “the Prophet preached to them” indicates direct exhortation, while the phrase “and ordered them to give charity” indicates instruction. This indicates that the Prophet (peace and blessings be upon him) told them that by giving alms their sins would be forgiven.
As for the partition, there is no harm in not having a curtain between the imam and women attending the religious lesson, for women’s faces are not considered `awrah (that is, they are not forbidden to be exposed). What is forbidden is privacy with the woman who is lawful for one to marry (ajnabiyyah). Looking at women is permissible when necessary and when Islamic proprieties, such as lowering the gaze, are observed. Moreover, when a woman intends to attend such assemblies of knowledge and teaching, she should not apply cosmetics, which arouse temptations.”