Ask HN: Slack alternative for orgs with compliance requirements?

Slack is near universal, but is not HIPAA compliant, and many financial organizations must record employee communications.

We examined Rocket chat, but the quality of the product is not there and the server requirements are absurd. Mattermost lacks essential requirements like LDAP integration on its basic edition.

Our requirements are literally just to be able to have team chats that keep centralized history. Does anything like this exist?