https://techcrunch.com/2017/09/07/microsoft-and-adobe-announce-an-expanded-partnership-around-adobe-sign-and-microsoft-teams/

Almost exactly a year ago, Microsoft and Adobe announced a strategic partnership around Microsoft’s Azure cloud and Adobe’s Marketing Cloud. That, however, was only a first step for the two companies. Today, they are announcing a major expansion of this partnership that sees them collaborating around e-signatures and team communications.

Specifically, this expanded deal means that Adobe Sign will become Microsoft’s preferred e-signature solution, with integrations into Office 365 and Dynamics 365, while Microsoft Teams — the company’s Slack competitor — will become the preferred collaboration service for the Adobe Creative Cloud, Document Cloud and Experience Cloud.