External collaboration is a platform feature that lets users communicate with people outside their organization through a managed system, such as chat, meetings, shared channels, or guest access. It is designed to make business communication easier while keeping activity inside an admin-controlled environment. In security terms, it extends the organization’s trust boundary beyond its own accounts and devices.
This matters because attackers can abuse that trust boundary for social engineering. A malicious external account may appear in a familiar workspace, impersonate helpdesk staff, and use routine support language to persuade a user to approve a request, share a code, or start a remote-control session. The platform itself may be working as intended; the risk comes from identity abuse and user consent. Defenders reduce exposure by limiting external access, tightening guest permissions, requiring strong identity verification for support, and using Conditional Access or tenant-bound support tools. In practice, external collaboration is convenient, but it must be treated as a security control point, not just a productivity feature.