How to Handle Subject Access Requests in Microsoft 365 (DSAR Guide)

Subject Access Requests (DSARs) are no longer an occasional compliance burden  they are a growing operational challenge, this also applies for organisations heavily reliant on Microsoft 365.

As data volumes increase and communication channels expand across Outlook, Teams, SharePoint, and OneDrive, responding to DSARs in a compliant, efficient, and defensible way has become significantly more complex.

At GRC Hub, we work with organisations navigating exactly this challenge: helping them manage Microsoft-based DSARs faster, more accurately, and with less strain on internal teams. In practice, around 95% of the organisations we support operate within Microsoft 365 environments, making it a core focus of our DSAR delivery approach.

Depending on client requirements, our engagements are flexible. In some cases, we securely extract and process data within our own environment to reduce internal overhead. In others, we operate directly within the client’s Microsoft 365 tenancy using their tech stack and security tooling ensuring alignment with internal controls, data residency requirements, and governance frameworks. This flexibility allows us to tailor our approach based on risk appetite, security considerations, and operational preference.

In this guide, we explore:

• Why DSARs are becoming harder to manage in Microsoft environments
• The common pitfalls organisations face
• How to approach DSARs across Microsoft 365
• And how specialist support can significantly reduce risk and effort

Why DSARs Can Be Complex in Microsoft 365

On paper, Microsoft provides a rich suite of tools to search and export data. However, in practice, DSARs in Microsoft 365 environments quickly become time-consuming and difficult to manage.

This is largely due to:

1. Data Sprawl Across Systems

Personal data isn’t stored in one place. It sits across:

• Exchange Online (emails and calendars)
• Microsoft Teams (chat messages, call logs, attachments)
• SharePoint Online (files, collaboration spaces)
• OneDrive (user-generated content)

Each of these platforms stores data differently, requiring separate search strategies.

2. Unstructured Data

Unlike structured systems (e.g. CRMs), Microsoft environments contain unstructured data:

• Email threads
• Chat conversations
• Document drafts
• Attachments with embedded personal data

This makes it harder to locate all relevant data and increases the risk of missing something.

3. Volume and Duplication

Search results often return:

• Thousands of documents
• Multiple duplicate versions
• Irrelevant or near-duplicate content

This creates a heavy review burden for internal teams.

4. Legal and Redaction Challenges

DSAR responses must:

• Remove third-party data
• Consider legal privilege
• Apply exemptions appropriately

Doing this manually at scale is both slow and error-prone.

Common Pitfalls When Handling Microsoft DSARs

Many organisations rely on Microsoft eDiscovery or manual exports but still encounter challenges such as:

• Over-collection of data leading to unnecessary review effort
• Inconsistent search approaches across different team members
• Manual review bottlenecks delaying responses
• Inadequate redaction processes increasing regulatory risk
• Missed deadlines due to process inefficiencies

While Microsoft provides powerful tools, they are not a complete DSAR solution they require expertise, structure, and operational support to use effectively.

A Practical Approach to Microsoft 365 DSAR Handling

A defensible and efficient DSAR process in Microsoft environments typically follows five key stages:

1. Scoping the Request

Before searching anything, organisations should:

• Clarify the scope of the request
• Identify relevant custodians (users)
• Define date ranges and subject areas

A well-scoped request reduces unnecessary data collection later.

2. Targeted Data Collection (Using Microsoft Tools)

Using Microsoft Purview eDiscovery, organisations can:

• Run keyword searches across mailboxes and sites
• Apply filters to reduce irrelevant results
• Export responsive datasets

However, without experience, searches often:

• Return too much data
• Miss key variations of names or identifiers

This is where structured search strategies are critical especially in large Microsoft tenancies with complex data structures.

3. Data Processing & Culling

Once data is collected, it needs to be refined by:

• Removing duplicates
• Filtering irrelevant files
• Structuring datasets for review

This step is often overlooked but can reduce review volumes significantly particularly when dealing with high-volume Microsoft exports.

4. Review & Redaction

This is the most resource-intensive stage.

Key requirements include:

• Identifying personal data relating to the requester
• Removing third-party personal data
• Applying exemptions (e.g. legal privilege)
• Ensuring consistency across reviewers

Without specialist tooling, this is typically done manually which is slow and risky.

5. Response & Audit Trail

Finally, organisations must:

• Provide the data in a clear format
• Include required explanatory information
• Maintain an audit trail of decisions

Regulators increasingly expect organisations to demonstrate how decisions were made not just provide data.

Why Internal Teams Struggle at Scale

Even well-resourced organisations find DSARs challenging in Microsoft environments because:

• Data protection teams aren’t eDiscovery specialists
• IT teams aren’t trained in legal decision-making
• Operational teams don’t have time for large-scale reviews

This often leads to:

• Delays
• Inconsistent outputs
• Increased regulatory exposure

How GRC Hub Supports Microsoft-Based DSARs

At GRC Hub, we combine data protection expertise with practical delivery capability, helping organisations handle DSARs efficiently within Microsoft ecosystems.

Given that the vast majority of our clients operate Microsoft 365, our delivery model is built specifically around these environments, whether working within your tenancy or managing secure data handling externally.

We typically support in three ways:

1. Process Optimisation & Assurance

We review your current DSAR approach and:

• Map Microsoft data sources
• Improve search and collection strategies
• Introduce defensible workflows

This is ideal for organisations wanting to retain DSARs internally but improve efficiency.

2. Training for Microsoft DSAR Handling

We provide hands-on training covering:

• Effective use of Microsoft Purview eDiscovery
• Keyword strategy and search optimisation
• Defensible review and redaction techniques

This enables teams to handle DSARs with greater confidence and consistency.

See Training Case Study

3. Fully Managed DSAR Service

For organisations under pressure, we deliver a complete end-to-end DSAR solution, including:

• Scoping and data mapping
• Microsoft 365 data collection (within your tenancy or via secure transfer)
• Processing and deduplication
• Review by specialist analysts
• Redaction using advanced tooling
• Final response preparation

By combining optimised eDiscovery workflows with experienced reviewers, we typically:

Process DSARs 3–4x faster than in-house teams
Reduce internal workload significantly
Deliver defensible, regulator-ready outputs
Adapt to your preferred delivery model (in-tenant or external handling)