Guest access lets people outside your organization join selected Teams with their own email identity—typically suppliers, auditors, or clients. Done well, it replaces insecure "forward this ZIP" email; done carelessly, it spreads data to unmanaged accounts.
Guests vs external access
| Approach | Best for |
|---|---|
| Guest (Azure B2B) | Ongoing collaboration in specific teams/channels |
| Anonymous meeting join | One-off webinars with lobby control |
| SharePoint sharing links | File-only sharing without full Teams membership |
Guests are invited people, not members of your employee directory. They see only the teams you add them to.
Safe invitation workflow
1. Sponsor inside your org owns the guest relationship (account manager, project lead).
2. Invite to a dedicated team or channel—not your company-wide default team.
3. Set expiration or review guests quarterly; remove when projects end.
4. Align with sensitivity labels and DLP so guests cannot exfiltrate restricted content.
5. Train guests: no screenshots of confidential data if contracts forbid it.
Admin controls to configure
- Whether only owners can invite guests.
- Domain allow/block lists for guest email domains.
- Conditional Access on guest sign-ins (MFA requirements).
- Access reviews (higher tiers) for periodic attestation.
Common mistakes
- Adding guests to company-wide teams with HR or leadership chatter.
- Leaving former vendors on teams for years.
- Sharing "Anyone with the link" files when guest membership would be auditable.
Licensing
Guest access capabilities depend on tenant settings and guest licensing rules Microsoft publishes for B2B collaboration. For tenant hardening alongside guest rollout, use M365 Deals or contact.
