Dynamic Distribution Groups

Manage dynamic distribution groups whose membership is automatically calculated based on recipient filters. Unlike static distribution groups, dynamic groups update their membership as user attributes change in Azure AD.

Note: Dynamic group membership is calculated when email is sent to the group, not in real-time. Preview membership to verify filters work as expected.

Dynamic Group List

How Dynamic Groups Work

1. Define filter — Set conditions based on user attributes (department, location, etc.).
2. Email sent to group — User sends a message to the group address.
3. Membership calculated — Exchange evaluates the filter against all recipients.
4. Message delivered — Message is delivered to all users matching the filter.

Common Filters

Department-Based

Include all users in a specific department:

• All users where Department = “Sales”
• All users where Department = “Engineering”
• Combined: Department = “Sales” OR Department = “Marketing”

Location-Based

Include all users in a specific location:

• All users where Office = “Seattle”
• All users where StateOrProvince = “California”
• All users where CountryOrRegion = “United States”

Company-Based

For multi-company tenants:

• All users where Company = “Contoso”
• All users where Company = “Fabrikam”

Custom Attribute-Based

Use custom attributes for flexible grouping:

• ExtensionAttribute1 = “ProjectAlpha”
• ExtensionAttribute2 = “VPN-Users”

Recipient Types

Include specific recipient types in the filter:

• Users with mailboxes — Standard user mailboxes
• Mail users — Users with external email addresses
• Mail contacts — External contacts in the GAL
• Groups — Other distribution groups

Filter Syntax

Simple Filters

Use the admin center to build filters with dropdown conditions and values.

Advanced Filters

Use OPATH filter syntax for complex conditions:

• Combine multiple conditions with -and / -or
• Use comparison operators (-eq, -ne, -like)
• Reference any recipient attribute

Preview Membership

Before relying on a dynamic group, preview the calculated membership:

• View the list of users who currently match the filter
• Verify expected users are included
• Check that unintended users are excluded
• Preview is a point-in-time snapshot

Best Practices

• Keep filters simple — Complex filters are harder to troubleshoot and audit.
• Preview before deploying — Always verify membership before using the group.
• Use standard attributes — Department and Office are more reliable than custom attributes.
• Document filter logic — Record what each dynamic group is intended to capture.
• Test with email — Send test messages to verify delivery to expected recipients.

API Reference

GET /api/exchange/dynamic-distribution-groups List dynamic distribution groups

POST /api/exchange/dynamic-distribution-groups Create dynamic distribution group

PUT /api/exchange/dynamic-distribution-groups/:id Update group filter

GET /api/exchange/dynamic-distribution-groups/:id/preview Preview calculated membership

DELETE /api/exchange/dynamic-distribution-groups/:id Delete dynamic distribution group