Is it permissible for an Imam to deliver a lecture to a group of women in one room without a barrier, or must the lecture be delivered via a screen?

It is permissible for a man to deliver a lecture to women in the same hall without a barrier, provided that the women adhere to complete hijab (covering the face and hands), do not speak in a soft, alluring manner, and there is no fear of temptation from either side. However, it is preferable to have a barrier, as it is further from temptation and more comfortable for the women.