For years, Zimbra called itself open source, but in reality it, all it did, was to published released code dumps from time to time. Many attempts to make outside code contributions simple have been killed by various owning entities (Yahoo, VMWare, Telligent) and we were also stuck with Perforce and ReviewBoard, which we could not open to the outside world.
Over the last year we have been breaking apart large perforce projects into smaller git repos (and then combining some of them again), rewriting internal tools and build scripts, separating Network code from FOSS code. Now, we are finally a real open source company. All our FOSS code is on github and anyone can submit pull requests. It’s all here: https://github.com/Zimbra/