Hi Maggie,

When I looked at the general information which came up on Google it said:

"Yammer is an enterprise social networking service used for private communication within organizations. Access to a Yammer network is determined by a user's Internet domain so that only individuals with approved email addresses may join their respective networks."

I'm not sure whether it would work outside of an organisation, or how or even whether it would work in Joe's scenario. The project members might have to all get an email address from the same provider.

Your suggestion for free discussion sites might be better. I don't know enough about either those or the Yammer option.