An archived, public mailing list for GNU Taler is hosted at https://lists.gnu.org/mailman/listinfo/taler (archive). You can send messages to the list at taler@gnu.org.
Team members are generally reachable at LASTNAME@taler.net. All of us support receiving GnuPG encrypted e-mails.
You can find some team members in the IRC channel #taler on irc.freenode.net.
We track open feature requests and bugs in our Bug tracker, which is shared with the GNUnet project. You can also report bugs or feature requests to the mailing list.
You can reach a group of team members handling general inquiries at contact AT taler.net.
For non-technical commercial requests, please contact ceo AT taler.net.