Replying to Messages in the Mailing List Archives
Discussion of Spectrum takes place on mailing lists.
Make sure to Reply All when replying to messages, so that the message is sent to the mailing list and not just to the person you reply to.
Getting a copy of a message
You may want to reply to a mailing list message that you do not have a copy of in your mail client, because you are not subscribed to the list or because you subscribed after the message was sent.
To do this, find the message you want to reply to in the public-inbox list archives, click on the "reply" link at the bottom of the message, then click the "mbox" link. Save the result to a file, then open it in your mail client. This should import the message and allow you to Reply All to it as normal.