Mattermost, works quite good. It is also pretty simple to set up and deploy. [0]: https://github.com/mattermost/mattermost-server https://github.com/mattermost

Mattermost, works quite good. It is also pretty simple to set up and deploy. [0]: https://github.com/mattermost/mattermost-server https://github.com/mattermost/mattermost-server EDIT: just read your post entireley. >> 'My company does not want to use yet another free Slack alternative on GitHub' So that one is not what you are looking for. But I keep the post in case anyone is interested in it...