[office-js][office-js-preview] (Outlook) Document contentId property for the read surface (DefinitelyTyped#74233)

Author: samantharamon

types/office-js-preview/index.d.ts

@@ -13076,17 +13076,15 @@ declare namespace Office {
          *
          * **Important**:
          *
-         * - The `contentId` property is only supported in Outlook on the web and Outlook on Windows (new and classic (preview)).
+         * - The `contentId` property is only supported in Outlook on the web, the new Outlook on Windows, and classic Outlook on Windows (preview).
          * To preview the `contentId` property in classic Outlook on Windows, your Outlook client must run Version 2510 (Build 19312.20000)
          * or later and must be on the Beta Channel. For more information, see {@link https://aka.ms/Msft365InsiderProgram | Microsoft 365 Insider Program}.
          *
-         * - Starting November 15, 2025, changes to how inline images are represented in the HTML body of Outlook emails in
-         * Outlook on the web and the new Outlook on Windows will begin rolling out to production users.
+         * - Changes to how inline images are represented in the HTML body of Outlook emails in Outlook on the web and the new Outlook on Windows released on November 15, 2025.
          * Previously, the attachment ID of the image appeared in the `src` attribute of the applicable `<img>` element.
-         * After the change, the image will be represented by a content ID (`cid`) in the `src` attribute instead.
-         * As a result, you'll need to update your add-in's parsing logic if you parse the attachment ID from the HTML editor or
-         * get the Base64 value of the image from the URL in the `src` attribute. For more information, see
-         * {@link https://devblogs.microsoft.com/microsoft365dev/changes-to-inline-images-in-outlook | Changes to inline image representation in Outlook on the web and new Outlook for Windows}.
+         * Now, the image is represented by a content ID (`cid`) in the `src` attribute instead.
+         * If you parse the attachment ID from the HTML editor or get the Base64-encoded value of the image from the URL in the `src` attribute, you must update your add-in's parsing logic.
+         * For more information, see {@link https://devblogs.microsoft.com/microsoft365dev/changes-to-inline-images-in-outlook | Changes to inline image representation in Outlook on the web and new Outlook for Windows}.
          */
         contentId: string;
         /**
@@ -13144,6 +13142,24 @@ declare namespace Office {
          * Gets a value that indicates the attachment's type.
          */
         attachmentType: MailboxEnums.AttachmentType | string;
+        /**
+         * Gets the content identifier of an inline attachment.
+         *
+         * @remarks
+         *
+         * **Important**:
+         *
+         * - The `contentId` property is only supported in Outlook on the web, the new Outlook on Windows, and classic Outlook on Windows (preview).
+         * To preview the `contentId` property in classic Outlook on Windows, your Outlook client must run Version 2510 (Build 19312.20000)
+         * or later and must be on the Beta Channel. For more information, see {@link https://aka.ms/Msft365InsiderProgram | Microsoft 365 Insider Program}.
+         *
+         * - Changes to how inline images are represented in the HTML body of Outlook emails in Outlook on the web and the new Outlook on Windows released on November 15, 2025.
+         * Previously, the attachment ID of the image appeared in the `src` attribute of the applicable `<img>` element.
+         * Now, the image is represented by a content ID (`cid`) in the `src` attribute instead.
+         * If you parse the attachment ID from the HTML editor or get the Base64-encoded value of the image from the URL in the `src` attribute, you must update your add-in's parsing logic.
+         * For more information, see {@link https://devblogs.microsoft.com/microsoft365dev/changes-to-inline-images-in-outlook | Changes to inline image representation in Outlook on the web and new Outlook for Windows}.
+         */
+        contentId: string;
         /**
          * Gets the MIME content type of the attachment.
          *

types/office-js/index.d.ts

@@ -12992,17 +12992,15 @@ declare namespace Office {
          *
          * **Important**:
          *
-         * - The `contentId` property is only supported in Outlook on the web and Outlook on Windows (new and classic (preview)).
+         * - The `contentId` property is only supported in Outlook on the web, the new Outlook on Windows, and classic Outlook on Windows (preview).
          * To preview the `contentId` property in classic Outlook on Windows, your Outlook client must run Version 2510 (Build 19312.20000)
          * or later and must be on the Beta Channel. For more information, see {@link https://aka.ms/Msft365InsiderProgram | Microsoft 365 Insider Program}.
          *
-         * - Starting November 15, 2025, changes to how inline images are represented in the HTML body of Outlook emails in
-         * Outlook on the web and the new Outlook on Windows will begin rolling out to production users.
+         * - Changes to how inline images are represented in the HTML body of Outlook emails in Outlook on the web and the new Outlook on Windows released on November 15, 2025.
          * Previously, the attachment ID of the image appeared in the `src` attribute of the applicable `<img>` element.
-         * After the change, the image will be represented by a content ID (`cid`) in the `src` attribute instead.
-         * As a result, you'll need to update your add-in's parsing logic if you parse the attachment ID from the HTML editor or
-         * get the Base64 value of the image from the URL in the `src` attribute. For more information, see
-         * {@link https://devblogs.microsoft.com/microsoft365dev/changes-to-inline-images-in-outlook | Changes to inline image representation in Outlook on the web and new Outlook for Windows}.
+         * Now, the image is represented by a content ID (`cid`) in the `src` attribute instead.
+         * If you parse the attachment ID from the HTML editor or get the Base64-encoded value of the image from the URL in the `src` attribute, you must update your add-in's parsing logic.
+         * For more information, see {@link https://devblogs.microsoft.com/microsoft365dev/changes-to-inline-images-in-outlook | Changes to inline image representation in Outlook on the web and new Outlook for Windows}.
          */
         contentId: string;
         /**
@@ -13061,6 +13059,24 @@ declare namespace Office {
          * Gets a value that indicates the attachment's type.
          */
         attachmentType: MailboxEnums.AttachmentType | string;
+        /**
+         * Gets the content identifier of an inline attachment.
+         *
+         * @remarks
+         *
+         * **Important**:
+         *
+         * - The `contentId` property is only supported in Outlook on the web, the new Outlook on Windows, and classic Outlook on Windows (preview).
+         * To preview the `contentId` property in classic Outlook on Windows, your Outlook client must run Version 2510 (Build 19312.20000)
+         * or later and must be on the Beta Channel. For more information, see {@link https://aka.ms/Msft365InsiderProgram | Microsoft 365 Insider Program}.
+         *
+         * - Changes to how inline images are represented in the HTML body of Outlook emails in Outlook on the web and the new Outlook on Windows released on November 15, 2025.
+         * Previously, the attachment ID of the image appeared in the `src` attribute of the applicable `<img>` element.
+         * Now, the image is represented by a content ID (`cid`) in the `src` attribute instead.
+         * If you parse the attachment ID from the HTML editor or get the Base64-encoded value of the image from the URL in the `src` attribute, you must update your add-in's parsing logic.
+         * For more information, see {@link https://devblogs.microsoft.com/microsoft365dev/changes-to-inline-images-in-outlook | Changes to inline image representation in Outlook on the web and new Outlook for Windows}.
+         */
+        contentId: string;
         /**
          * Gets the MIME content type of the attachment.
          *