Message Trace Support Using Graph API Reaches Public Preview with Throttling and Migration Path

Microsoft has announced that Message Trace support using the Graph API is now available in public preview, marking a significant shift in how administrators can monitor and troubleshoot email flow within Exchange Online. This new RESTful API replaces the existing Message Trace support using the Reporting Webservice API, which is scheduled for deprecation on April 6, 2026. The move is a direct response to community feedback aimed at improving the overall Message Trace experience, with general availability (GA) planned for rollout by late January 2026, with completion expected within the first week of February.

What Changed: From Reporting Webservice to Graph API

The core change is the migration from the legacy Reporting Webservice API to the modern Microsoft Graph API. The Graph API provides a unified, RESTful endpoint for accessing Exchange Online data, including message tracing capabilities. This shift aligns with Microsoft's broader strategy to consolidate its API surface under Microsoft Graph, offering a more consistent and scalable platform for developers and administrators.

The new exchangeMessageTrace resource type in Microsoft Graph beta allows you to trace email messages throughout your Exchange Online organization. You can access the official documentation here: exchangeMessageTrace resource type - Microsoft Graph beta | Microsoft Learn.

For organizations already using the Reporting Webservice, migration is mandatory. Microsoft notes that all new organizations onboarding to Exchange Online no longer have access to the Reporting Webservice API by default, as part of the ongoing migration effort. The deprecation timeline is firm: Message Trace and Message Trace Detail support using the Reporting Webservice will begin deprecating on April 6, 2026. This gives existing users approximately 25 months to transition their automation and workflows to the Graph API.

Provider Comparison: Graph API vs. Reporting Webservice

The shift to Graph API represents a move from a siloed, service-specific API to a unified platform. The Reporting Webservice was designed specifically for Exchange Online reporting, while the Graph API is a multi-service endpoint that can access data across Microsoft 365, including Azure Active Directory, SharePoint, and Teams. This unification simplifies API management for organizations using multiple Microsoft cloud services, as they can consolidate authentication, authorization, and API calls under a single Graph endpoint.

From a technical perspective, the Graph API uses OAuth 2.0 for authentication, which is more modern and secure than the legacy authentication methods often required by older Reporting Webservice integrations. The Graph API also supports granular permissions, allowing administrators to scope access to specific data sets, which enhances security posture.

However, the transition requires careful planning. The Reporting Webservice API had its own throttling limits and query structures, which will differ from the Graph API's rate-based throttling. Organizations must update their codebases, SDKs, and automation scripts to use the Graph SDKs or direct REST calls to the exchangeMessageTrace endpoint.

Throttling Limits: Ensuring Fairness and Service Availability

A critical aspect of the new Graph API implementation is the introduction of strict throttling limits to prevent misuse and ensure service availability for all tenants. Microsoft will enforce a rate-based throttling limit of 100 query requests per 5-minute running window for a tenant. This limit applies collectively to both message trace and message trace detail queries. If the request rate is below 100 requests in any 5-minute window, throttling is not applied.

This throttling is designed to protect Exchange Online resources from abuse and provide a predictable experience. It's important to distinguish between query requests and result size: a single query can return up to 5,000 results. Therefore, the maximum number of results retrievable in a 5-minute window is 500,000 (100 queries × 5,000 results). With strategic query distribution, organizations can retrieve up to 144 million results daily (500,000 results per 5 minutes × 288 five-minute windows in a 24-hour period).

For administrators using PowerShell cmdlets, the throttling limits are mirrored in the Get-MessageTraceV2 and Get-MessageTraceDetailV2 cmdlets, which are also subject to the 100 requests per 5-minute limit. This ensures consistency between direct API calls and PowerShell automation.

Business Impact and Migration Considerations

The migration to Graph API has several business implications. First, organizations must audit their existing Message Trace usage to understand their current request patterns. If automation scripts query more frequently than the 100 requests per 5-minute threshold, they will need to be updated to stay within the new limits. This may require batching queries, implementing exponential backoff, or redesigning data collection workflows.

Second, the deprecation timeline provides a clear window for migration, but the process may involve significant development effort. Organizations should start by reviewing the Graph API documentation and testing the new endpoints in a non-production environment. Microsoft's Graph SDKs (available for .NET, Java, Python, and other languages) can simplify the transition by providing higher-level abstractions over the REST API.

Third, the shift to Graph API aligns with broader cloud-native trends where APIs are consolidated under a single, scalable platform. This can reduce long-term maintenance costs and improve interoperability with other cloud services. However, it also means that organizations must invest in learning the Graph API's authentication, permission models, and query syntax.

Finally, the throttling limits emphasize the need for efficient data retrieval strategies. Organizations should design their monitoring and reporting systems to work within these constraints, potentially using incremental data pulls or leveraging other Microsoft 365 data export services for large-scale analytics.

Conclusion

The public preview of Message Trace support using Graph API is a pivotal step in modernizing Exchange Online management. It offers a more unified, secure, and scalable API while setting a clear migration path away from the legacy Reporting Webservice. The introduced throttling limits require careful planning but are essential for maintaining service quality across all tenants. Organizations should begin their migration planning immediately, leveraging the official Graph API documentation and Microsoft's migration guidance to ensure a smooth transition before the April 2026 deprecation deadline.