R help - Aug 2017 - R-SIG-Debian keeps telling me I must be subscribed to post, but I am

I'm not sure where to post this. I subscribed to R-Sig-Debian this morning,
I hope the email excerpt below proves this:
  Welcome to the R-SIG-Debian at r-project.org mailing list!

   To post to this list, send your message to:

    r-sig-debian at r-project.org

   General information about the mailing list is at:

    https://stat.ethz.ch/mailman/listinfo/r-sig-debian

   If you ever want to UNSUBSCRIBE [my caps] or change your options (eg,
   switch to [etc.]

I then sent a post asking for help about installing Tidyverse on Ubuntu.
Immediately, I got back the reply:
  We are sorry that we can no longer accept postings from
   NON-SUBSCRIBERS, due to spamming and lack of moderator resources.

   Best regards, the R-SIG-Debian moderators,
   r-sig-debian-owner at r-project.org

What's going on? Have I conflated two addresses, or something? I sent a
reply to r-sig-debian-owner at r-project.org , giving the above evidence that
I was subscribed, but although the moderator was quick to reject my post,
he/she didn't answer.

Confused.

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