Honestly, email lists are better than Discord in a lot of ways. There are standard ways to make them indexable via Google, you can use whatever app you want to, threads are a first class feature most people use, and since it's so open filtering can be very powerful. Bots are also extremely easy to write since basically every programming language has the ability to send email (and usually also to receive it via at least one email server protocol which isn't controlled by the distribution list, but by the bot writer).
