💡 Our Technical Review in summary
Summary
- Message ID: MC1103608
- Topic: Update to the Entra ID B2B (business-to-business) guest authentication flow.
- Timeline: Rolling out from early July 2025 through late December 2025.
- Core Change: Microsoft is refining the sign-in sequence for guest users to provide better visual context regarding which credentials they are using and which tenant they are accessing.
Impact
- User Experience: When a guest user signs into your tenant, they will first see your organization’s branded sign-in screen. After entering their email, they will be redirected to their own organization’s (home tenant) sign-in page to enter their credentials.
- Branding Clarity: This update ensures users see their home organization’s branding and URL when entering passwords or performing MFA, reducing confusion about which account is being used.
- Security Awareness: By clearly displaying the home tenant’s URL and branding during the credential-entry phase, the risk of users entering credentials into unfamiliar or phishing-prone interfaces is reduced.
- Administrative Impact: There are no changes to existing B2B policies, cross-tenant access settings, or conditional access requirements. This is primarily a UI/UX flow optimization.
Action Required
- Administrative Action: No direct technical configuration or administrative action is required to enable this feature. It will be enabled automatically by Microsoft.
- Documentation Update: Review and update internal “Guest Access” or “Vendor Onboarding” documentation. If your current guides show old screenshots of the sign-in flow, they should be updated to reflect the new redirected branding experience.
- Help Desk Awareness: Inform your IT support team of this change. Users might report the “redirection” as unexpected behavior if they are used to the previous unified sign-in experience.
- Monitoring: Keep an eye on the Message Center post for the “new documentation” Microsoft promised to provide prior to the rollout to understand any edge cases.
Microsoft Official Update
Service: N/A
Category: planForChange
Severity: normal
This message only applies to tenants that use B2B (business-to-business) collaboration.
We will start rolling out an update to the authentication experience for guest users signing in to your tenant for collaboration via Microsoft Entra ID B2B collaboration.
[When this will happen:]
General Availability (Worldwide, GCC, GCC High, DoD): We will begin rolling out early July 2025 and expect to complete by late December 2025.
[How this will affect your organization:]
After this rollout, guest users will begin signing in on your branded sign-in screen. After entering their email and clicking Next, they will be redirected to their home organization’s sign-in page to enter their credentials. This ensures they see the branding and URL endpoint of their home tenant, making clearer whose credentials to use. After successful authentication, they will be redirected back to your organization to complete the sign-in process.
This change enhances usability and reduces user confusion during cross-tenant sign-in.
[What you need to do to prepare:]
No administrative action is required prior to this rollout. We recommend you review your current B2B collaboration configuration to understand the potential impact and update any relevant documentation to guide users.
Before rollout, we will update this post with new documentation.
