Team or Project mailbox in GroupWise

We have client with GroupWise 2012 we are trying to move to GW2014
as with all these things Exchange has cropped up in the discussion... again!!

Another company has put forward Office 365 Sharepoint solution

One of the requirements is better Project or Job based communications - Sharepoint Site mailboxes has been suggested.
and several people like the idea and its been thrown at us as longstanding partner to see if we can deliver this

Is there functionality in GW that can help with this?
initial thinking is that creating a Job/Project mailbox might do the job but since the client has been shown Exchange Sharepoint system
we need to investigate the full capabilities