Regarding lecturing by woman devotees: I have informed you that in the service of the Lord there is no distinction of caste or creed, color, or sex. In the Bhagavad-gita, the Lord especially mentions that even a woman who has taken seriously is also destined to reach Him. We require a person who is in the knowledge of Krishna, that is the only qualification of a person speaking. It doesn't matter what he is.
Letter to Jaya Govinda, 8 February, 1968