If someone is looking for someone who can give speeches, is female speakers a bad idea, given the general opinion among Muslims that there shalt be no free-mixing? Is there a Hadith that says that free-mixing of the sexes is verboten? If so where is it and is it authentic?
The evils that can come from free mixing is actually quite clear, as is the evidence for it being haram. Among them is the prohibition of looking at each other (except if family members). And the Prophet ordered to wait to leave the Masjid until the women left so that there is no mixing, as well as he (peace and blessings be upon him) said:
Because those in the first row are farther away from the women, while those in the back row are closer, and those of the women in the first row are close to the men than those in the back row. So lastly I say that free mixing is un-Islamic, and if a man and women (not of the family) have to meet then keep it professional (No touching, kissing, flirting etc.).
Primary Source: islamweb.net.