In order to improve the ability to support brms and the community using it, I will be deprecating the brms-users google group and migrate to the official Stan forums at
http://discourse.mc-stan.org/. There, brms now has its own tag called "Interfaces - brms", which you should use to tag brms-related questions. Me and the rest of the Stan team will continue answering your questions there.
I will leave brms-users open for some more time until I will close the google group for new questions. The old questions and answers will of course remain visible.
I look forward to seeing you on the Stan Forums!