As Bill White has mentioned, you really need to first determine where the move to Junk is being done, and resolve the issue there. If your email provider is Comcast, then if you check your webmail you should see the same messages in Junk as you see in the email client, then it's most probable that Comcast is doing that assignment. And if that's the case I'd whitelist anything coming from groups.io using whatever mechanism they use.
The fact that you say Junk makes me think you're using Thunderbird, and if so you can either train its Junk filtering or put in a whitelist item for anything originating from groups.io and never sending that to junk.
Brian - Windows 10 Pro, 64-Bit, Version 20H2, Build 19042
To think is to differ.