XMPP Discussion
There are many active discussion venues for Jabber/XMPP developers, system administrators, and end users. In addition to discussion lists and web forums specific to particular codebases, the following general venues are hosted by the XMPP Standards Foundation. These lists are all easily searchable at jabber.markmail.org.
For End Users
JUser@jabber.org email list -- for discussion about use of IM clients (subscribe | archives)
Jabber support chatroom -- real-time chat about using Jabber/XMPP technologies (webchat | join | logs)
For System Admins
JAdmin@jabber.org email list -- for discussion about installing and configuring Jabber/XMPP server software (subscribe | archives)
Operators@xmpp.org email list -- for discussion about day-to-day operation of the Jabber/XMPP communications network (subscribe | archives)
Operators chatroom -- real-time chat about the Jabber/XMPP network (webchat | join | logs)
For Developers
JDev@jabber.org email list -- for discussion about software development using Jabber/XMPP technologies (subscribe | archives)
Standards@xmpp.org email list -- for general discussion about XMPP protocols (subscribe | archives)
Developer chatroom -- real-time chat about software and protocols (webchat | join | logs)
Special-Purpose Venues
The following special-purpose mailing lists provide low-volume, high-quality discussion among developers interested in specific aspects of XMPP technologies.
BOSH@xmpp.org email list -- for discussion about the HTTP binding for XMPP as defined in XEP-0124 and XEP-0206 (subscribe | archives)
Jingle@xmpp.org email list -- for discussion about the use of XMPP as a signalling channel for multimedia session negotiation (voice, video, file sharing, etc.) as defined in XEP-0166 and related extensions (subscribe | archives)
Mobile@xmpp.org email list -- for discussion about the applications and optimization of XMPP technologies for mobile networks (subscribe | archives)
MUC@xmpp.org email list -- for discussion about the XMPP extensions for multi-user chat (subscribe | archives)
PubSub@xmpp.org email list -- for discussion about the XMPP extensions for publish-subscribe and personal eventing such as data syndication and extended presence (subscribe | archives)
Security@xmpp.org email list -- for discussion about security issues related to XMPP, including encryption, authentication, and spam (subscribe | archives)
Social@xmpp.org email list -- for discussion about the use of XMPP in social networking applications such as microblogging (subscribe | archives)
SIP-XMPP@xmpp.org email list -- for discussion about interworking between SIP and XMPP (subscribe | archives)
WS-XMPP@xmpp.org email list -- for discussion about the use of XMPP in real-time web services, middleware, cloud computing, etc. (subscribe | archives)
All of these venues are completely free and open to any interested individual.