We use Discourse for forum support - it is great and most of our communication is in there. Our forum has a community of 200,000 developers and we can easily handle it with Discourse.
Founder & CEO - AppGyver
1%Stacklist Startups Are Using Discourse
Discourse is the 100% open source discussion platform. It works as a mailing list, a discussion forum and a long-form chat room.
Visit the website: https://www.discourse.org/