diff --git a/types/office-js/index.d.ts b/types/office-js/index.d.ts
index 0b6186eb8c..90c4583e67 100644
--- a/types/office-js/index.d.ts
+++ b/types/office-js/index.d.ts
@@ -1826,6 +1826,8 @@ declare namespace Office {
          * Triggers when an attachment is added to or removed from an item.
          * 
          * [Api set: Mailbox Preview]
+         * 
+         * @beta
          */
         AttachmentsChanged,
         /**
@@ -1924,6 +1926,8 @@ declare namespace Office {
          * Triggers when the OfficeTheme is changed in Outlook.
          * 
          * [Api set: Mailbox Preview]
+         * 
+         * @beta
          */
         OfficeThemeChanged,
         /**
@@ -8565,6 +8569,8 @@ declare namespace Office {
      * <table><tr><td>{@link https://docs.microsoft.com/outlook/add-ins/understanding-outlook-add-in-permissions | Minimum permission level}</td><td>ReadItem</td></tr>
      *
      * <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/#extension-points | Applicable Outlook mode}</td><td>Compose or read</td></tr></table>
+     * 
+     * @beta
      */
     interface AttachmentContent {
         /**
@@ -9394,7 +9400,7 @@ declare namespace Office {
          * 
          * In addition to this signature, this method also has the following signature:
          * 
-         * `getAsync(coerciontype: Office.CoercionType, callback: (result: AsyncResult<Office.Body>) => void): void;`
+         * `getAsync(names: string[], callback: (result: AsyncResult<Office.InternetHeaders>) => void): void;`
          * 
          * @param names The names of the internet headers to be returned.
          * @param options Optional. An object literal that contains one or more of the following properties:
@@ -9405,6 +9411,28 @@ declare namespace Office {
          * @beta
          */
         getAsync(names: string[], options?: Office.AsyncContextOptions, callback?: (result: AsyncResult<Office.InternetHeaders>) => void): void;
+        /**
+         * Given an array of internet header names, this method returns a dictionary containing those internet headers and their values. 
+         * If the add-in requests an x-header that is not available, that x-header will not be returned in the results. 
+         *
+         * [Api set: Mailbox Preview]
+         *
+         * @remarks
+         * <table><tr><td>{@link https://docs.microsoft.com/outlook/add-ins/understanding-outlook-add-in-permissions | Minimum permission level}</td><td>ReadItem</td></tr>
+         *
+         * <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/#extension-points | Applicable Outlook mode}</td><td>Compose or read</td></tr></table>
+         * 
+         * In addition to this signature, this method also has the following signature:
+         * 
+         * `getAsync(names: string[], options?: Office.AsyncContextOptions, callback?: (result: AsyncResult<Office.InternetHeaders>) => void): void;`
+         * 
+         * @param names The names of the internet headers to be returned.
+         * @param callback Optional. When the method completes, the function passed in the callback parameter is called with a single parameter, 
+         *                 asyncResult, which is an Office.AsyncResult object.
+         * 
+         * @beta
+         */
+        getAsync(names: string[], callback?: (result: AsyncResult<Office.InternetHeaders>) => void): void;
         /**
          * Given an array of internet header names, this method removes the specified headers from the internet header collection.
          *
@@ -9417,7 +9445,7 @@ declare namespace Office {
          * 
          * In addition to this signature, this method also has the following signature:
          * 
-         * `getAsync(coerciontype: Office.CoercionType, callback: (result: AsyncResult<Office.Body>) => void): void;`
+         * `removeAsync(names: string[], callback: (result: AsyncResult<Office.Body>) => void): void;`
          * 
          * @param names The names of the internet headers to be removed.
          * @param options Optional. An object literal that contains one or more of the following properties:
@@ -9428,6 +9456,27 @@ declare namespace Office {
          * @beta
          */
         removeAsync(names: string[], options?: Office.AsyncContextOptions, callback?: (result: AsyncResult<Office.InternetHeaders>) => void): void;
+        /**
+         * Given an array of internet header names, this method removes the specified headers from the internet header collection.
+         *
+         * [Api set: Mailbox Preview]
+         *
+         * @remarks
+         * <table><tr><td>{@link https://docs.microsoft.com/outlook/add-ins/understanding-outlook-add-in-permissions | Minimum permission level}</td><td>ReadWriteItem</td></tr>
+         *
+         * <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/#extension-points | Applicable Outlook mode}</td><td>Compose</td></tr></table>
+         * 
+         * In addition to this signature, this method also has the following signature:
+         * 
+         * `removeAsync(names: string[], options?: Office.AsyncContextOptions, callback: (result: AsyncResult<Office.Body>) => void): void;`
+         * 
+         * @param names The names of the internet headers to be removed.
+         * @param callback Optional. When the method completes, the function passed in the callback parameter is called with a single parameter, 
+         *                 asyncResult, which is an Office.AsyncResult object.
+         * 
+         * @beta
+         */
+        removeAsync(names: string[], callback?: (result: AsyncResult<Office.InternetHeaders>) => void): void;
         /**
          * Sets the specified internet headers to the specified values.
          * 
@@ -9441,24 +9490,45 @@ declare namespace Office {
          *
          * <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/#extension-points | Applicable Outlook mode}</td><td>Compose</td></tr>
          *
-         * <tr><td>Errors</td><td>DataExceedsMaximumSize - The data parameter is longer than 1,000,000 characters.</td></tr><tr><td></td><td>InvalidFormatError - The options.coercionType parameter is set to Office.CoercionType.Html and the message body is in plain text.</td></tr></table>
-         * 
          * In addition to this signature, this method also has the following signatures:
          * 
-         * `setAsync(data: string, options: Office.AsyncContextOptions & CoercionTypeOptions): void;`
+         * `setAsync(headers: string, callback: (result: AsyncResult<void>) => void): void;`
          * 
-         * `setAsync(data: string, callback: (result: AsyncResult<void>) => void): void;`
-         * 
-         * `setAsync(data: string): void;`
-         *
          * @param headers The names and corresponding values of the headers to be set. Should be a dictionary object with keys being the names of the 
          *                internet headers and values being the values of the internet headers.
          * @param options Optional. 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 method.
          * @param callback Optional. When the method completes, the function passed in the callback parameter is called with a single parameter of type Office.AsyncResult.
          *                  Any errors encountered will be provided in the asyncResult.error property.
+         * 
+         * @beta
          */
         setAsync(headers: Object, options?: Office.AsyncContextOptions, callback?: (result: AsyncResult<void>) => void): void;
+        /**
+         * Sets the specified internet headers to the specified values.
+         * 
+         * The setAsync method creates a new header if the specified header does not already exist; otherwise, the existing value is replaced with 
+         * the new value.
+         *
+         * [Api set: Mailbox Preview]
+         *
+         * @remarks
+         * <table><tr><td>{@link https://docs.microsoft.com/outlook/add-ins/understanding-outlook-add-in-permissions | Minimum permission level}</td><td>ReadWriteItem</td></tr>
+         *
+         * <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/#extension-points | Applicable Outlook mode}</td><td>Compose</td></tr>
+         *
+         * In addition to this signature, this method also has the following signatures:
+         * 
+         * `setAsync(headers: string, options?: Office.AsyncContextOptions, callback: (result: AsyncResult<void>) => void): void;`
+         * 
+         * @param headers The names and corresponding values of the headers to be set. Should be a dictionary object with keys being the names of the 
+         *                internet headers and values being the values of the internet headers.
+         * @param callback Optional. When the method completes, the function passed in the callback parameter is called with a single parameter of type Office.AsyncResult.
+         *                  Any errors encountered will be provided in the asyncResult.error property.
+         * 
+         * @beta
+         */
+        setAsync(headers: Object, callback?: (result: AsyncResult<void>) => void): void;
     }
 
     /**
@@ -13008,6 +13078,8 @@ declare namespace Office {
          * <table><tr><td>{@link https://docs.microsoft.com/outlook/add-ins/understanding-outlook-add-in-permissions | Minimum permission level}</td><td>ReadItem</td></tr>
          *
          * <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/#extension-points | Applicable Outlook mode}</td><td>Message Compose</td></tr></table>
+         * 
+         * @beta
          */
         internetHeaders: Office.InternetHeaders;
         /**
@@ -14105,6 +14177,8 @@ declare namespace Office {
          * <table><tr><td>{@link https://docs.microsoft.com/outlook/add-ins/understanding-outlook-add-in-permissions | Minimum permission level}</td><td>ReadItem</td></tr>
          *
          * <tr><td>{@link https://docs.microsoft.com/outlook/add-ins/#extension-points | Applicable Outlook mode}</td><td>Message Read</td></tr></table>
+         * 
+         * @beta
          */
         internetHeaders: Office.InternetHeaders;
         /**