You can subscribe to the following mailing lists:
First is <[email protected]>, which is the main discussion group of the LDP.
Another is the <[email protected]> list, which is for questions about DocBook use including markup and transformations. If you run into trouble with a particular markup tag, you can send your question here for answers.
You can subscribe to either list by sending a request message to either <[email protected]> or <[email protected]>. The subject of your message should read "subscribe" (no quotes). To remove yourself from the list, send an E-mail with the subject of "unsubscribe" to <[email protected]> or <[email protected]>.
If you are interested in DocBook beyond the simple markup of your LDP document, you may want to consider joining one of the OASIS DocBook mailing lists. Please see http://docbook.org/mailinglist/index.html for more information.