sorry for the ill placed post with the confirmation message.
The original notification message from the mailing list system which
told me that my membership had been disabled also said:
"To re-enable your membership, you can simply respond to this message
(leaving the Subject: line intact) …"
Without thinking I did that, and for some reason, my email client sent
it to the mailing list and not to dng-request@??? as I had
expected. In the raw mail of the original mailing list's notification
message there is no Reply-To field which could have caused that,
only "X-BeenThere: dng@???", but I don't know what it means.