diff --git a/types/office-js-preview/index.d.ts b/types/office-js-preview/index.d.ts
index 52f9aa2b3b4add..03320e55ccf7ec 100644
--- a/types/office-js-preview/index.d.ts
+++ b/types/office-js-preview/index.d.ts
@@ -11703,9 +11703,14 @@ declare namespace Office {
          *
          * **{@link https://learn.microsoft.com/office/dev/add-ins/outlook/outlook-add-ins-overview#extension-points | Applicable Outlook mode}**: Appointment Organizer
          *
-         * **Important**: In Outlook on the web and the new Outlook on Windows, users can select the **Upload and share** option to upload an attachment to OneDrive and
+         * **Important**:
+         *
+         * - In Outlook on the web and the new Outlook on Windows, users can select the **Upload and share** option to upload an attachment to OneDrive and
          * include a link to the file in the mail item. However, since only a link is included, `getAttachmentsAsync` doesn't return this attachment.
          *
+         * - For attachments of type `Office.MailboxEnums.AttachmentType.Item`, the size and serialized content returned by `getAttachmentsAsync` might differ between calls
+         * made from an `OnMessageSend` or `OnAppointmentSend` event handler. To reliably detect attachment changes, handle the `OnMessageAttachmentsChanged` or `OnAppointmentAttachmentsChanged` event instead.
+         *
          * @param options - An object literal that contains one or more of the following properties:-
          *        `asyncContext`: Developers can provide any object they wish to access in the callback function.
          * @param callback - Optional. When the method completes, the function passed in the `callback` parameter is called with a single parameter of
@@ -11723,9 +11728,14 @@ declare namespace Office {
          *
          * **{@link https://learn.microsoft.com/office/dev/add-ins/outlook/outlook-add-ins-overview#extension-points | Applicable Outlook mode}**: Appointment Organizer
          *
-         * **Important**: In Outlook on the web and the new Outlook on Windows, users can select the **Upload and share** option to upload an attachment to OneDrive and
+         * **Important**:
+         *
+         * - In Outlook on the web and the new Outlook on Windows, users can select the **Upload and share** option to upload an attachment to OneDrive and
          * include a link to the file in the mail item. However, since only a link is included, `getAttachmentsAsync` doesn't return this attachment.
          *
+         * - For attachments of type `Office.MailboxEnums.AttachmentType.Item`, the size and serialized content returned by `getAttachmentsAsync` might differ between calls
+         * made from an `OnMessageSend` or `OnAppointmentSend` event handler. To reliably detect attachment changes, handle the `OnMessageAttachmentsChanged` or `OnAppointmentAttachmentsChanged` event instead.
+         *
          * @param callback - Optional. When the method completes, the function passed in the `callback` parameter is called with a single parameter of
          *                 type `Office.AsyncResult`. If the call fails, the `asyncResult.error` property will contain an error code with the reason for
          *                 the failure. If the call succeeds, an array of `AttachmentDetailsCompose` objects is returned in the `asyncResult.value` property.
@@ -14696,6 +14706,8 @@ declare namespace Office {
          *
          * **{@link https://learn.microsoft.com/office/dev/add-ins/outlook/outlook-add-ins-overview#extension-points | Applicable Outlook mode}**: Compose or Read
          *
+         * **Important**: In classic Outlook on Windows, custom properties saved to a mail item in read mode remain accessible while the item is being forwarded.
+         *
          * @param name - The name of the custom property to be returned.
          */
         get(name: string): any;
@@ -14716,6 +14728,8 @@ declare namespace Office {
          * **{@link https://learn.microsoft.com/office/dev/add-ins/outlook/understanding-outlook-add-in-permissions | Minimum permission level}**: **read item**
          *
          * **{@link https://learn.microsoft.com/office/dev/add-ins/outlook/outlook-add-ins-overview#extension-points | Applicable Outlook mode}**: Compose or Read
+         *
+         * **Important**: In classic Outlook on Windows, custom properties saved to a mail item in read mode remain accessible while the item is being forwarded.
          */
         getAll(): any;
         /**
@@ -20683,6 +20697,9 @@ declare namespace Office {
          * - In Outlook on the web and the new Outlook on Windows, users can select the **Upload and share** option to upload an attachment to OneDrive and
          * include a link to the file in the mail item. However, since only a link is included, `getAttachmentsAsync` doesn't return this attachment.
          *
+         * - For attachments of type `Office.MailboxEnums.AttachmentType.Item`, the size and serialized content returned by `getAttachmentsAsync` might differ between calls
+         * made from an `OnMessageSend` or `OnAppointmentSend` event handler. To reliably detect attachment changes, handle the `OnMessageAttachmentsChanged` or `OnAppointmentAttachmentsChanged` event instead.
+         *
          * @param options - An object literal that contains one or more of the following properties:-
          *        `asyncContext`: Developers can provide any object they wish to access in the callback function.
          * @param callback - Optional. When the method completes, the function passed in the `callback` parameter is called with a single parameter of
@@ -20711,6 +20728,9 @@ declare namespace Office {
          * - In Outlook on the web and the new Outlook on Windows, users can select the **Upload and share** option to upload an attachment to OneDrive and
          * include a link to the file in the mail item. However, since only a link is included, `getAttachmentsAsync` doesn't return this attachment.
          *
+         * - For attachments of type `Office.MailboxEnums.AttachmentType.Item`, the size and serialized content returned by `getAttachmentsAsync` might differ between calls
+         * made from an `OnMessageSend` or `OnAppointmentSend` event handler. To reliably detect attachment changes, handle the `OnMessageAttachmentsChanged` or `OnAppointmentAttachmentsChanged` event instead.
+         *
          * @param callback - Optional. When the method completes, the function passed in the `callback` parameter is called with a single parameter of
          *                 type `Office.AsyncResult`. If the call fails, the `asyncResult.error` property will contain an error code with the reason for
          *                 the failure. If the call succeeds, an array of `AttachmentDetailsCompose` objects are returned in the `asyncResult.value` property.
diff --git a/types/office-js/index.d.ts b/types/office-js/index.d.ts
index 03fbd743d4392e..badb59e8cd2c50 100644
--- a/types/office-js/index.d.ts
+++ b/types/office-js/index.d.ts
@@ -11632,9 +11632,14 @@ declare namespace Office {
          *
          * **{@link https://learn.microsoft.com/office/dev/add-ins/outlook/outlook-add-ins-overview#extension-points | Applicable Outlook mode}**: Appointment Organizer
          *
-         * **Important**: In Outlook on the web and the new Outlook on Windows, users can select the **Upload and share** option to upload an attachment to OneDrive and
+         * **Important**:
+         *
+         * - In Outlook on the web and the new Outlook on Windows, users can select the **Upload and share** option to upload an attachment to OneDrive and
          * include a link to the file in the mail item. However, since only a link is included, `getAttachmentsAsync` doesn't return this attachment.
          *
+         * - For attachments of type `Office.MailboxEnums.AttachmentType.Item`, the size and serialized content returned by `getAttachmentsAsync` might differ between calls
+         * made from an `OnMessageSend` or `OnAppointmentSend` event handler. To reliably detect attachment changes, handle the `OnMessageAttachmentsChanged` or `OnAppointmentAttachmentsChanged` event instead.
+         *
          * @param options - An object literal that contains one or more of the following properties:-
          *        `asyncContext`: Developers can provide any object they wish to access in the callback function.
          * @param callback - Optional. When the method completes, the function passed in the `callback` parameter is called with a single parameter of
@@ -11652,9 +11657,14 @@ declare namespace Office {
          *
          * **{@link https://learn.microsoft.com/office/dev/add-ins/outlook/outlook-add-ins-overview#extension-points | Applicable Outlook mode}**: Appointment Organizer
          *
-         * **Important**: In Outlook on the web and the new Outlook on Windows, users can select the **Upload and share** option to upload an attachment to OneDrive and
+         * **Important**:
+         *
+         * - In Outlook on the web and the new Outlook on Windows, users can select the **Upload and share** option to upload an attachment to OneDrive and
          * include a link to the file in the mail item. However, since only a link is included, `getAttachmentsAsync` doesn't return this attachment.
          *
+         * - For attachments of type `Office.MailboxEnums.AttachmentType.Item`, the size and serialized content returned by `getAttachmentsAsync` might differ between calls
+         * made from an `OnMessageSend` or `OnAppointmentSend` event handler. To reliably detect attachment changes, handle the `OnMessageAttachmentsChanged` or `OnAppointmentAttachmentsChanged` event instead.
+         *
          * @param callback - Optional. When the method completes, the function passed in the `callback` parameter is called with a single parameter of
          *                 type `Office.AsyncResult`. If the call fails, the `asyncResult.error` property will contain an error code with the reason for
          *                 the failure. If the call succeeds, an array of `AttachmentDetailsCompose` objects is returned in the `asyncResult.value` property.
@@ -14624,6 +14634,8 @@ declare namespace Office {
          *
          * **{@link https://learn.microsoft.com/office/dev/add-ins/outlook/outlook-add-ins-overview#extension-points | Applicable Outlook mode}**: Compose or Read
          *
+         * **Important**: In classic Outlook on Windows, custom properties saved to a mail item in read mode remain accessible while the item is being forwarded.
+         *
          * @param name - The name of the custom property to be returned.
          */
         get(name: string): any;
@@ -14644,6 +14656,8 @@ declare namespace Office {
          * **{@link https://learn.microsoft.com/office/dev/add-ins/outlook/understanding-outlook-add-in-permissions | Minimum permission level}**: **read item**
          *
          * **{@link https://learn.microsoft.com/office/dev/add-ins/outlook/outlook-add-ins-overview#extension-points | Applicable Outlook mode}**: Compose or Read
+         *
+         * **Important**: In classic Outlook on Windows, custom properties saved to a mail item in read mode remain accessible while the item is being forwarded.
          */
         getAll(): any;
         /**
@@ -20387,6 +20401,9 @@ declare namespace Office {
          * - In Outlook on the web and the new Outlook on Windows, users can select the **Upload and share** option to upload an attachment to OneDrive and
          * include a link to the file in the mail item. However, since only a link is included, `getAttachmentsAsync` doesn't return this attachment.
          *
+         * - For attachments of type `Office.MailboxEnums.AttachmentType.Item`, the size and serialized content returned by `getAttachmentsAsync` might differ between calls
+         * made from an `OnMessageSend` or `OnAppointmentSend` event handler. To reliably detect attachment changes, handle the `OnMessageAttachmentsChanged` or `OnAppointmentAttachmentsChanged` event instead.
+         *
          * @param options - An object literal that contains one or more of the following properties:-
          *        `asyncContext`: Developers can provide any object they wish to access in the callback function.
          * @param callback - Optional. When the method completes, the function passed in the `callback` parameter is called with a single parameter of
@@ -20415,6 +20432,9 @@ declare namespace Office {
          * - In Outlook on the web and the new Outlook on Windows, users can select the **Upload and share** option to upload an attachment to OneDrive and
          * include a link to the file in the mail item. However, since only a link is included, `getAttachmentsAsync` doesn't return this attachment.
          *
+         * - For attachments of type `Office.MailboxEnums.AttachmentType.Item`, the size and serialized content returned by `getAttachmentsAsync` might differ between calls
+         * made from an `OnMessageSend` or `OnAppointmentSend` event handler. To reliably detect attachment changes, handle the `OnMessageAttachmentsChanged` or `OnAppointmentAttachmentsChanged` event instead.
+         *
          * @param callback - Optional. When the method completes, the function passed in the `callback` parameter is called with a single parameter of
          *                 type `Office.AsyncResult`. If the call fails, the `asyncResult.error` property will contain an error code with the reason for
          *                 the failure. If the call succeeds, an array of `AttachmentDetailsCompose` objects is returned in the `asyncResult.value` property.