From what I can see in the codebase, it doesn’t look like we sync Mailchimp Audience → Discourse yet. This does feel like something we can look into if more folks request for it.
Having this sync could work well with fixing that known issue mentioned in the OP.
As mentioned, with privacy concerns this can be a bit of an issue. Having done email verification first definitely feels like the way to go. I also understand that there’s a tiny bit of friction having to click “Subscribe” on the banner, but for now we think this is the best option to keep both ends happy. 