Incorrect Conversation ID Returned by Microsoft Graph API

Hi @Swapnil Jagtap,

Thank you for providing the details. From the information shown, it is not yet possible to conclude that Microsoft Graph is returning an incorrect conversationId.

conversationId is an Exchange/Outlook conversation identifier for the conversation to which the mailbox item belongs. Outlook groups messages that share the same subject and belong to the same thread; matching subjects alone do not establish that two messages must have the same ID. Conversations can also contain branches and items from different folders or stores. The underlying Outlook Conversation object is an aggregated object rather than a separate message object.

Ref: Managing Outlook Items as Conversations | Microsoft Learn

Please verify:

• Compare the exact same message in the same mailbox, not merely two messages with the same subject. In particular, confirm:
• The mailbox accessed by /me
• Whether it is a user or shared mailbox
• The message’s internetMessageId
• Whether the message was moved, copied, imported, or restored
• Whether the subject was changed while replying

Microsoft documents that changing the subject of a reply can result in a different conversation ID for that message. Ref: PidTagConversationTopic Canonical Property | Microsoft Learn

• Reproduce with a minimal request

GET https://graph.microsoft.com/v1.0/me/messages/{message-id}?$select=id,internetMessageId,subject,conversationId,conversationIndex,parentFolderId,createdDateTime,lastModifiedDateTime
client-request-id: {new-GUID}

The attachment expansion and other selected fields are not required to isolate this behavior.

For each test, record: 

• HTTP request-id
• HTTP Date
• Your client-request-id
• Authentication type: delegated or application
• Mail permission used
• The source and format of the expected conversation ID

Review the response:

•  If the expected value belongs to another message, was taken from Outlook’s visual grouping, or uses a different ID format, the difference be expected.
• If both values were obtained for the same exact stored message, in the same mailbox, using the same ID format, and the difference is consistently reproducible, that would be unexpected and should be investigated as a possible service-side issue.
• The subject alone should not be used to determine the expected conversation.
• Treat conversationId as an opaque identifier; applications should not parse or construct it.

Ref: How to Debug Microsoft Graph API Calls - Dev Proxy | Microsoft Learn

If the mismatch remains after those checks, a Microsoft 365 administrator should open a support request and provide the unredacted identifiers, response headers, and sanitized request/response privately. Those details are required for Microsoft to correlate the Graph request with the mailbox operation.

For more reference, please visit:

• Microsoft Graph message resource
• Get message using Microsoft Graph
• Managing Outlook items as conversations
• Convert Outlook IDs between EWS and REST formats
• Microsoft Graph debugging and diagnostic guidance