[Admin] Rejecting messages from non-subscribed addresses

[John Gruber]

The most common problem with this mailing list seems to be that
people forget which address they've used to subscribe. Then, they
attempt to post a message from some other address, and the message
is rejected by the mailing list software.

E.g., if you subscribe to the list using the address
<joe at example.com>, then you must use that address to post to the
list.

Prior to today, such messages were discarded, but I, as the list
admin, was sent a notice of each. I'd send a private note to the
poster to tell them what had happened.

This is taking too much of my time, so I've configured Mailman to
automatically bounce such messages. However, as far as I can tell, I
can't configure the message that's sent with the bounce.

If this happens to you, you'll get a bounce with message that says:

    You are not allowed to post to this mailing list, and your message has
    been automatically rejected.  If you think that your messages are
    being rejected in error, contact the mailing list owner at
    markdown-discuss-owner at six.pairlist.net.

If you get such a message, the problem is almost certainly that you
sent your post using the wrong account.

-J.G.