@sun There was something called "apple tree project" that was an early attempt at building a federated competitor to StatusNet ... ATP had a built in webmail client on their demo server (AFAIK the only ATP server that ever existed). It may have had some other groupware features built in.

Unfortunately, it was apparently just one person doing the development and some of the features seemed like afterthoughts rather than well integrated.

At least I remember it by the ATP name. Searching GitHub brings up something totally different for that name.