Hi {{first_name}},
I'd like to propose a joint webinar on [[specific topic]]. You'd cover [[their angle or expertise area]], and I'd handle [[your angle or expertise area]]. The format: [[duration, e.g., "45 minutes plus Q&A"]], co-hosted and co-promoted.
On my end, I'd promote to [[your audience size and channels]]. Between our two audiences, we'd likely reach [[combined estimate]].
I can handle the logistics: registration page, hosting, and recording. Your only commitment would be showing up and sharing the invite with your list.
Does [[proposed timeframe]] work for your calendar?
[[Your name]]