the "eclipse.jwt" newsgroup on the eclipse.org news server. See corresponding forum and archives, and older archives before migration. Can be used to contact developers, but not used much.
If you are interested in receiving bug messages in your bugzilla account : there are three dummy mail-addresses for the components of JWT, named jwt.we-inbox@eclipse.org, jwt.desktop-inbox@eclipse.org, jwt.wam-inbox@eclipse.org , so copy this comma-separated list in Prefs / Email settings to your user watch list in Bugzilla.