A common tale of woe:
You can use Zapier or similar services to munge the two formats, but that's such a pain.
We've launched support to automatically detect when you're supplying Buttondown with a Discord webhook and munge it into the right format so that you can keep your server up to date with your newsletter's activity. Just spin up a new webhook in Discord, bring it over to Buttondown, and that is it.
Got another service like Discord that you want us to support? Let us know!