SC-401 - Retention and Data Lifecycle

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Retention Overview
Retention Labels
Retention Policies
Adaptive Scopes
Retention Precedence
Records Management
Disposition Review

Retention Overview

Microsoft Purview data lifecycle management helps organizations keep what they need and delete what they do not. Retention ensures that content is:

Preserved for the required period (regulatory, legal, business requirement)
Deleted when the retention period expires (to minimize data exposure and storage costs)

Two primary tools in Microsoft Purview for retention:

Tool	Scope	Granularity	User Visible
Retention Policies	Broad - applies to entire locations (all mailboxes, all SharePoint sites)	Location-level, cannot target specific documents	No - users do not see them
Retention Labels	Granular - applies to specific items (individual documents, emails)	Item-level settings override location-level policies	Yes - users can see and (if permitted) apply labels

Retention Labels

Retention labels provide item-level retention control. They can be manually applied by users, auto-applied by Purview based on conditions, or published for users to apply.

Retention Label Settings

Setting	Options
Retention period	Fixed period (days, months, years) from: creation date, last modification date, label applied date, or a custom event date
At end of retention period	Delete automatically, trigger disposition review, or do nothing (keep but allow deletion)
Classify as record	Mark item as a regulatory or standard record (restricts editing/deletion during retention)
Retention period start	When was the retention clock started (creation, modification, event)

Label Publishing vs. Auto-Apply

Method	How	Use Case
Publish to users	Create a label policy targeting users/locations; users manually apply in Office apps, SharePoint, OD, Outlook	Content that users know needs specific retention (contracts, legal docs)
Auto-apply based on SIT	Purview automatically applies the label when content containing the specified SITs is found	PII-containing documents that require 7-year retention for regulatory compliance
Auto-apply based on trainable classifier	Applies label to content matching a classifier (e.g., tax documents)	Category-based retention of documents that are hard to pattern-match
Auto-apply based on cloud attachments	Applies label to files shared as cloud attachments in Teams and Outlook	Ensuring collaboration content is retained
Default label in SP library	Site admin sets a default retention label for a document library	All documents in a specific library get the same retention

Retention labels survive content being moved between locations within Microsoft 365. If you move a labeled email from Exchange to Teams or a labeled document from one SharePoint site to another, the retention label stays with the item. Labels also travel within OneDrive sync when files are moved locally.

Retention Policies

Retention policies apply a single retention setting to an entire location (e.g., all Exchange mailboxes, all SharePoint sites). They are simpler than labels but cannot target individual documents.

Supported Locations

Exchange Online mailboxes (email, calendar, tasks)
SharePoint sites and document libraries
OneDrive accounts
Microsoft 365 Groups (mailbox + SharePoint site)
Teams channel messages (requires Teams-specific retention policy)
Teams private/shared channel messages
Teams chats (1:1 and group chats)
Viva Engage messages

Retain-Only vs. Retain-Then-Delete vs. Delete-Only

Action	Behavior
Retain for X years	Content is preserved for X years even if user deletes it (recoverable); after X years, content can be deleted normally
Retain for X years then delete	Content preserved for X years; then automatically deleted by the service
Delete content older than X years	No preservation - content older than X years is deleted (useful for reducing data exposure of old content)

For Teams and Viva Engage, retention policies must use dedicated Teams/Yammer locations - you cannot use Exchange policies to retain Teams messages. Teams messages (channel and chat) are actually stored in Exchange (in hidden mailbox folders), but retention for Teams is processed differently and requires Teams-specific policies to handle the data correctly.

Adaptive Scopes

Adaptive scopes allow retention policies and label policies to dynamically target users, groups, and sites based on Azure AD attributes and SharePoint properties, without having to manually maintain static lists.

Adaptive Scope Types

Scope Type	Targets	Example Query
Users	Azure AD user accounts based on user attributes	Department = "Finance" OR City = "New York"
SharePoint sites	SharePoint sites based on site properties	Site template = "Team site" AND created after 2022
Microsoft 365 Groups	M365 Groups based on group attributes	Group name contains "Legal"

Benefits of Adaptive Scopes

Automatically includes new users/sites that match the query when they are created
Automatically removes users/sites that no longer match (e.g., when someone leaves Finance)
Eliminates the need to manually add/remove users from static scope policies
Supports OPATH query syntax for complex targeting

Adaptive scopes require Azure AD Premium P1 (for user and group attribute-based queries). They are defined as reusable scope objects in the Purview portal that can be applied to multiple retention or label policies. Changes to the scope query take effect within 5-7 days as the scope member list is refreshed.

Retention Precedence

When multiple retention policies and/or labels apply to the same content, Microsoft Purview uses a retention precedence order to determine which settings win. The general principle is: preserve always wins over delete, and longer retention wins over shorter.

Precedence Order (Highest to Lowest)

Explicit retain over explicit delete: If one policy says retain and another says delete, retain wins
Longer retention period over shorter: Among multiple retain settings, the longest period wins
User deletion over automatic policy deletion: Explicit deletions by users happen after retention expires; policy auto-deletions happen at period end
Retention label over retention policy: An item-level label overrides the location-level policy for that specific item

Practical Example

A SharePoint file has:

A retention policy: retain all SharePoint content for 3 years
A retention label: retain for 7 years (applied because it contains legal contract SITs)

The file will be retained for 7 years (label wins - it's longer and item-level), not 3 years. The retention policy still protects all other unlabeled files in SharePoint for 3 years.

The retention precedence rules mean you can safely layer retention policies and labels. Use retention policies for baseline coverage (all mailboxes retained for 3 years), and use labels for specific high-value content that needs longer or different retention. Labels never shorten what the policy would preserve - only extend or add granularity.

Records Management

Records management in Microsoft Purview handles formal records - documents that must be preserved in their original state for legal or regulatory reasons. Records management features are available in Purview Records Management (separate from Data Lifecycle Management).

Record Declaration Types

Type	Description	Editing/Deletion
Record (standard)	Declared via retention label with "Mark as record" enabled	Edit locked; deletion locked until retention period expires (disposition review can unlock)
Regulatory record	Declared via retention label with "Mark as regulatory record" - highest restriction	Edit AND delete locked; even admins cannot remove the record status - requires regulatory authority approval to delete

Regulatory records are the strictest form of retention control in Microsoft Purview. Once a regulatory record label is applied, it cannot be removed by any administrator - not even Global Admin. This is by design for industries like financial services (SEC 17a-4 compliance) and healthcare (HIPAA records retention). Be extremely careful deploying regulatory record labels - apply thorough testing before production rollout.

Disposition Review

Disposition review allows human reviewers to inspect content at the end of its retention period before it is permanently deleted. This bridges compliance requirements with legal review processes.

Disposition review workflow:

A retention label is configured with "trigger a disposition review" at the end of retention
When items reach end of retention, a disposition review task is created in Purview Records Management - Disposition
Assigned reviewers inspect the items and choose: delete, extend retention, apply a different label, or no action
Items awaiting disposition are preserved until a reviewer takes action
All disposition decisions are logged for audit purposes

Disposition reviews can have multiple stages - for example, a first review by department managers, then a second review by legal counsel before deletion. Multi-stage approval is configured in the retention label settings. Proof of disposal (a disposition certificate) is generated automatically when items are deleted after review, satisfying regulatory requirements for documented destruction.

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