Mattermost team here, thanks for the mention! Mattermost had threaded messaging since 2015, it used to be called "Replies" and we renamed it "Threaded messages

Mattermost team here, thanks for the mention! Mattermost had threaded messaging since 2015, it used to be called "Replies" and we renamed it "Threaded messages" in April 2016: https://about.mattermost.com/mattermost-3-4-7/ https://about.mattermost.com/mattermost-3-4-7/ If anyone wants to try it out, you can join https://demo.mattermost.com/ https://demo.mattermost.com/ Mattermost is an open source, private cloud Slack-alternative. We're "Slack-compatible, not Slack limited" and you'll find all the core features of Slack plus many benefits added by the open source community--like markdown support, translation into 11 languages, multi-team accounts, searchable hashtags and much more: https://www.mattermost.org/what-slack-might-learn-from-its-open-source-alternative/ https://www.mattermost.org/what-slack-might-learn-from-its-o...