Evolution of Extranet Sites in Modern SharePoint

Introduction

In the Classic SharePoint era, organizations commonly created dedicated Extranet sites to collaborate securely with partners, vendors, or clients outside their corporate network. However, with the evolution of Modern SharePoint Online, this concept has been replaced with a simplified and more secure external sharing model.

This article explains how the traditional Extranet architecture has evolved, how Modern SharePoint handles external collaboration, and how to configure secure sharing with external users.

1. Extranet Concept in Classic SharePoint

In Classic SharePoint (on-premises or early SharePoint Online), an Extranet site was a separate site collection or web application specifically configured for external access.

Typical features included

Hosted separately (e.g., https://extranet.company.com)
Configured with Forms-Based Authentication (FBA) or ADFS
Managed manually by administrators with custom user roles
Segregated from the internal network for security reasons
Required heavy infrastructure maintenance and governance

This setup ensured security but involved complex management - administrators had to handle authentication zones, user databases, and firewall configurations.

2. Transition in Modern SharePoint

With Modern SharePoint Online (Microsoft 365), Microsoft has eliminated the need for separate Extranet sites. Instead, collaboration with external users is handled via External Sharing and Guest Access, built directly into the platform.

Any modern SharePoint site - Team Site or Communication Site - can be securely shared with external users by adjusting sharing settings at the tenant and site level.

3. External Sharing in Modern SharePoint

Modern SharePoint offers a streamlined external sharing experience:

Tenant-level control: Admins define whether external sharing is allowed and what level of access is permitted.
Site-level configuration: Site owners can decide if their specific site can be shared externally.
User-level invitations: External users receive an invitation via email and sign in with their existing Microsoft or business account.
Guest management: All external users are automatically added and managed within Microsoft Entra ID (Azure AD) as Guest Users.

This approach transforms every modern SharePoint site into a potential Extranet site, without the need for additional infrastructure.

4. Feature Comparison

Feature / Capability	Classic Extranet Site	Modern SharePoint External Sharing
Architecture	Separate site collection or web app	Regular Team/Communication site
Authentication	FBA / ADFS	Microsoft Entra ID (Azure AD) Guest Access
User Management	Manual partner user creation	Automatic guest user management
Access Control	Custom web app permissions	Per-site sharing settings
Governance	Manual and decentralized	Centralized via Microsoft 365 Compliance Center
Security	Network-based	Identity and policy-based (MFA, Conditional Access)

5. How to Share a Modern SharePoint Site with External Users

Follow these steps to securely share a site with an external (guest) user:

Step 1: Enable External Sharing for the Site

Go to the SharePoint Admin Center.
Select Sites → Active sites.
Choose the site you want to share.
Under the Policies tab, click Sharing.
Set the sharing level to one of the following:
- Only people in your organization
- Existing guests
- New and existing guests (recommended for Extranet-type sites)
- Anyone (most permissive – use cautiously)

Step 2: Share the Site

Open the SharePoint site you want to share.
Click the Settings icon → Site permissions.
Click Invite people → Add members to group or Share site only.
Enter the external user’s email address.
Choose Member or Visitor role depending on required access.
Click Add or Share.
The user receives an invitation email and joins as a guest upon acceptance.

Step 3: Verify Guest Access

Open Microsoft Entra ID (Azure AD) - Users - Guest users to confirm the user appears in the directory.
You can manage permissions and remove guests anytime from the site’s Site Permissions panel.

6. Limitations of External (Guest) Users

While external sharing is powerful, guest users have certain restrictions compared to internal users.

Area	Limitation / Behavior
Licensing	Guests don’t consume full Microsoft 365 licenses. They get limited access via Azure AD B2B.
Access Scope	Guests can only access shared sites or files — not the full SharePoint environment.
Search	Guests can search only within the site(s) they have access to, not across tenant-wide content.
Sharing	Guests cannot share items with other users unless explicitly allowed by admin.
OneDrive	Guests do not get personal OneDrive storage.
Microsoft Teams	Guests can join Teams linked to shared sites but have limited capabilities (no Planner, limited app integration).
Power Automate / Power Apps	Guests cannot run flows or apps using internal connections unless explicitly permitted and licensed.
Access Expiration	Admins can enforce expiration policies to automatically remove inactive guests.
Conditional Access	Guest access may be restricted by organization’s security or device compliance policies.

These controls ensure that collaboration remains secure while preventing excessive data exposure.

7. Security and Governance Enhancements

Modern SharePoint integrates deeply with Microsoft 365’s security and compliance capabilities, enabling organizations to manage collaboration without compromising data protection.

Key Security Features

Conditional Access Policies
Multi-Factor Authentication (MFA)
Guest Access Expiration Policies
Sensitivity Labels
Audit Logs and Reports

8. Best Practices for External Sharing

1. Define Clear Sharing Policies

Allow external sharing only when necessary.
Configure tenant-wide limits for external sharing (e.g., Existing guests only).

2. Use Site-Specific External Sharing

Enable external sharing only for designated collaboration sites.

3. Apply Sensitivity Labels

Use Microsoft Purview Sensitivity Labels to automatically control external sharing permissions.

4. Enforce Conditional Access

Require MFA for all guest users.
Restrict access from unmanaged devices.

5. Monitor and Review Guest Access

Regularly review and clean up inactive guest accounts.
Use Access Reviews in Entra ID for automated clean-up.

6. Prefer Teams Integration for Collaboration

For real-time collaboration and communication, use Microsoft Teams connected to SharePoint.
For document sharing only, SharePoint alone is sufficient.

Aspect	Classic SharePoint	Modern SharePoint
Extranet Concept	Separate Environment	External sharing within the tenant
Complexity	High	Low (policy-based)
Security	Network-based	Identity-based
Collaboration	Limited	Integrated with the M365 ecosystem
Governance	Manual	Centralized and automated

Conclusion

The concept of a separate “Extranet site” is now obsolete in Modern SharePoint Online. Microsoft’s modern approach leverages per-site external sharing, guest access, and Microsoft Entra ID integration to provide a secure, scalable, and compliant collaboration experience.

This evolution simplifies management, enhances security, and aligns with today’s identity-driven cloud architecture — eliminating the need for traditional Extranet configurations.