The mailing list Textbook-l is now also on gmane
http://mail.wikipedia.org/mailman/listinfo/textbook-l
Use the newsserver "news.gmane.org"
The name of the newsgroup is
"gmane.org.wikimedia.textbook"
gmane is a mailing list to usenet interfase
For posting to the newsgroup you must be a list member. The first time you post to the newsgroup you will receive an email for verification of your email address, which is normal. If you work by means of the newsgroup you probably no longer wants to receive the messages by email. To disable email delivery go to "Edit Options". ( see http://mail.wikipedia.org/mailman/listinfo/textbook-l )
All the other Wikipedia mailing lists are also available on gmane. Search for wikipedia on the list of newsgroups of news.gmane.org