Quick Ref: Syncing Outlook Pins via Microsoft Graph MAPI Properties

#Core Concept

Microsoft Graph does not have a native email pinning endpoint. Instead, the official Outlook client tracks pinned states using an underlying MAPI property called PidTagRenewTime (historically PR_RenewTime2), mapped as SystemTime 0x0F02.

• Pinned: Value is set to a far-future date: 4500-01-01T00:00:00Z.
• Unpinned: Value is set back to the email's original receivedDateTime (or current timestamp).

#API Operations

1. Fetching Pin Status (GET)

Expand the target MAPI property using an OData filter when loading messages:

GET https://microsoft.com($filter=id eq 'SystemTime 0x0F02')

Parsing Logic: Check the returned singleValueExtendedProperties array. If an item matches id: "SystemTime 0x0F02" and its value starts with 4500, flag it as pinned in the UI layer and anchor it to the top.

2. Pinning an Email (PATCH)

PATCH https://microsoft.com{message-id}
Content-Type: application/json

{
  "singleValueExtendedProperties": [
    {
      "id": "SystemTime 0x0F02",
      "value": "4500-01-01T00:00:00Z"
    }
  ]
}

3. Unpinning an Email (PATCH)

PATCH https://microsoft.com{message-id}
Content-Type: application/json

{
  "singleValueExtendedProperties": [
    {
      "id": "SystemTime 0x0F02",
      "value": "2026-09-22T14:42:00Z" 
    }
  ]
}

#Agent Warning

Official Graph SDK libraries sometimes choke when serializing the singleValueExtendedProperties array on a PATCH. If updates fail to save, bypass the high-level SDK models and perform a raw HTTP request.