Invitation to speaker to speak at a conference / corporate event (unpaid).
[Company / Society] will be [having its annual [meeting / convention / conference] / [hosting a seminar] on [date]. The theme of the [meeting / convention / conference / seminar] is on [topic].
The [talk / panel discussion] will be around [number] minutes followed by a [number] minutes Q&A session. Around [number] people are expected to attend this event. The audience will consist of [company staff / top executives / clients / industry leaders / socialites / students / new joiners]. The event will officially start at [time] and finish at around [time].
invitation to speak,