Build your first Outlook add-in

Article
01/10/2023
8 minutes to read

In this article, you'll walk through the process of building an Outlook task pane add-in that displays at least one property of a selected message.

Create the add-in

You can create an Office Add-in by using the Yeoman generator for Office Add-ins or Visual Studio. The Yeoman generator creates a Node.js project that can be managed with Visual Studio Code or any other editor, whereas Visual Studio creates a Visual Studio solution. Select the tab for the one you'd like to use and then follow the instructions to create your add-in and test it locally.

Yeoman generator
Visual Studio

Prerequisites

Note

If you aren't familiar with Node.js or npm, you should start by setting up your development environment.

Node.js (the latest LTS version).
The latest version of Yeoman and the Yeoman generator for Office Add-ins. To install these tools globally, run the following command via the command prompt.
```
npm install -g yo generator-office
```
Note

Even if you've previously installed the Yeoman generator, we recommend you update your package to the latest version from npm.

Visual Studio Code (VS Code) or your preferred code editor
Outlook 2016 or later on Windows (connected to a Microsoft 365 account) or Outlook on the web

Create the add-in project

Run the following command to create an add-in project using the Yeoman generator.
```
yo office
```
Note

When you run the yo office command, you may receive prompts about the data collection policies of Yeoman and the Office Add-in CLI tools. Use the information that's provided to respond to the prompts as you see fit.

When prompted, provide the following information to create your add-in project.
- Choose a project type - Office Add-in Task Pane project
- Choose a script type - JavaScript
- What do you want to name your add-in? - My Office Add-in
- Which Office client application would you like to support? - Outlook
After you complete the wizard, the generator will create the project and install supporting Node components.

Tip

You can ignore the next steps guidance that the Yeoman generator provides after the add-in project's been created. The step-by-step instructions within this article provide all of the guidance you'll need to complete this tutorial.
Navigate to the root folder of the web application project.
```
cd "My Office Add-in"
```

Explore the project

The add-in project that you've created with the Yeoman generator contains sample code for a very basic task pane add-in.

The ./manifest.xml file in the root directory of the project defines the settings and capabilities of the add-in.
The ./src/taskpane/taskpane.html file contains the HTML markup for the task pane.
The ./src/taskpane/taskpane.css file contains the CSS that's applied to content in the task pane.
The ./src/taskpane/taskpane.js file contains the Office JavaScript API code that facilitates interaction between the task pane and Outlook.

Update the code

Open your project in VS Code or your preferred code editor.

Tip

On Windows, you can navigate to the root directory of the project via the command line and then enter code . to open that folder in VS Code. On Mac, you'll need to add the code command to the path before you can use that command to open the project folder in VS Code.

Open the file ./src/taskpane/taskpane.html and replace the entire <main> element (within the <body> element) with the following markup. This new markup adds a label where the script in ./src/taskpane/taskpane.js will write data.

<main id="app-body" class="ms-welcome__main" style="display: none;">
    <h2 class="ms-font-xl"> Discover what Office Add-ins can do for you today! </h2>
    <p><label id="item-subject"></label></p>
    <div role="button" id="run" class="ms-welcome__action ms-Button ms-Button--hero ms-font-xl">
        <span class="ms-Button-label">Run</span>
    </div>
</main>

In your code editor, open the file ./src/taskpane/taskpane.js and add the following code within the run function. This code uses the Office JavaScript API to get a reference to the current message and write its subject property value to the task pane.
```
// Get a reference to the current message
const item = Office.context.mailbox.item;

// Write message property value to the task pane
document.getElementById("item-subject").innerHTML = "<b>Subject:</b> <br/>" + item.subject;
```

Try it out

Note

Office Add-ins should use HTTPS, not HTTP, even when you are developing. If you are prompted to install a certificate after you run one of the following commands, accept the prompt to install the certificate that the Yeoman generator provides. You may also have to run your command prompt or terminal as an administrator for the changes to be made.

Run the following command in the root directory of your project. When you run this command, the local web server starts and your add-in will be sideloaded.
```
npm start
```
In Outlook, view a message in the Reading Pane, or open the message in its own window.
Choose the Home tab (or the Message tab if you opened the message in a new window), and then choose the Show Taskpane button in the ribbon to open the add-in task pane.

Note

If you receive the error "We can't open this add-in from localhost" in the task pane, follow the steps outlined in the troubleshooting article.
When prompted with the WebView Stop On Load dialog box, select OK.

Note

If you select Cancel, the dialog won't be shown again while this instance of the add-in is running. However, if you restart your add-in, you'll see the dialog again.
Scroll to the bottom of the task pane and choose the Run link to write the message subject to the task pane.

Next steps

Congratulations, you've successfully created your first Outlook task pane add-in! Next, learn more about the capabilities of an Outlook add-in and build a more complex add-in by following along with the Outlook add-in tutorial.

Prerequisites

Visual Studio 2019 with the Office/SharePoint development workload installed

Note

If you've previously installed Visual Studio 2019, use the Visual Studio Installer to ensure that the Office/SharePoint development workload is installed.
Microsoft 365

Note

If you do not have a Microsoft 365 subscription, you can get a free one by signing up for the Microsoft 365 developer program.

Create the add-in project

On the Visual Studio menu bar, choose File > New > Project.
In the list of project types under Visual C# or Visual Basic, expand Office/SharePoint, choose Add-ins, and then choose Outlook Web Add-in as the project type.
Name the project, and then choose OK.
Visual Studio creates a solution and its two projects appear in Solution Explorer. The MessageRead.html file opens in Visual Studio.

Explore the Visual Studio solution

When you've completed the wizard, Visual Studio creates a solution that contains two projects.

Project	Description
Add-in project	Contains only an XML manifest file, which contains all the settings that describe your add-in. These settings help the Office application determine when your add-in should be activated and where the add-in should appear. Visual Studio generates the contents of this file for you so that you can run the project and use your add-in immediately. You can change these settings any time by modifying the XML file.
Web application project	Contains the content pages of your add-in, including all the files and file references that you need to develop Office-aware HTML and JavaScript pages. While you develop your add-in, Visual Studio hosts the web application on your local IIS server. When you're ready to publish the add-in, you'll need to deploy this web application project to a web server.

Project

Description

Add-in project

Contains only an XML manifest file, which contains all the settings that describe your add-in. These settings help the Office application determine when your add-in should be activated and where the add-in should appear. Visual Studio generates the contents of this file for you so that you can run the project and use your add-in immediately. You can change these settings any time by modifying the XML file.

Web application project

Contains the content pages of your add-in, including all the files and file references that you need to develop Office-aware HTML and JavaScript pages. While you develop your add-in, Visual Studio hosts the web application on your local IIS server. When you're ready to publish the add-in, you'll need to deploy this web application project to a web server.

Update the code

MessageRead.html specifies the HTML that will be rendered in the add-in's task pane. In MessageRead.html, replace the <body> element with the following markup and save the file.

<body class="ms-font-m ms-welcome">
    <div class="ms-Fabric content-main">
        <h1 class="ms-font-xxl">Message properties</h1>
        <table class="ms-Table ms-Table--selectable">
            <thead>
                <tr>
                    <th>Property</th>
                    <th>Value</th>
                </tr>
            </thead>
            <tbody>
                <tr>
                    <td><strong>Id</strong></td>
                    <td class="prop-val"><code><label id="item-id"></label></code></td>
                </tr>
                <tr>
                    <td><strong>Subject</strong></td>
                    <td class="prop-val"><code><label id="item-subject"></label></code></td>
                </tr>
                <tr>
                    <td><strong>Message Id</strong></td>
                    <td class="prop-val"><code><label id="item-internetMessageId"></label></code></td>
                </tr>
                <tr>
                    <td><strong>From</strong></td>
                    <td class="prop-val"><code><label id="item-from"></label></code></td>
                </tr>
            </tbody>
        </table>
    </div>
</body>

Open the file MessageRead.js in the root of the web application project. This file specifies the script for the add-in. Replace the entire contents with the following code and save the file.

'use strict';

(function () {

    Office.onReady(function () {
        // Office is ready
        $(document).ready(function () {
            // The document is ready
            loadItemProps(Office.context.mailbox.item);
        });
    });

    function loadItemProps(item) {
        // Write message property values to the task pane
        $('#item-id').text(item.itemId);
        $('#item-subject').text(item.subject);
        $('#item-internetMessageId').text(item.internetMessageId);
        $('#item-from').html(item.from.displayName + " &lt;" + item.from.emailAddress + "&gt;");
    }
})();

Open the file MessageRead.css in the root of the web application project. This file specifies the custom styles for the add-in. Replace the entire contents with the following code and save the file.
```
html,
body {
    width: 100%;
    height: 100%;
    margin: 0;
    padding: 0;
}

td.prop-val {
    word-break: break-all;
}

.content-main {
    margin: 10px;
}
```

Update the manifest

Open the XML manifest file in the Add-in project. This file defines the add-in's settings and capabilities.
The <ProviderName> element has a placeholder value. Replace it with your name.
The DefaultValue attribute of the <DisplayName> element has a placeholder. Replace it with My Office Add-in.
The DefaultValue attribute of the <Description> element has a placeholder. Replace it with My First Outlook add-in.

Save the file.

...
<ProviderName>John Doe</ProviderName>
<DefaultLocale>en-US</DefaultLocale>
<!-- The display name of your add-in. Used on the store and various places of the Office UI such as the add-ins dialog. -->
<DisplayName DefaultValue="My Office Add-in" />
<Description DefaultValue="My First Outlook add-in"/>
...

Try it out

Using Visual Studio, test the newly created Outlook add-in by pressing F5 or choosing the Start button. The add-in will be hosted locally on IIS.
In the Connect to Exchange email account dialog box, enter the email address and password for your Microsoft account and then choose Connect. When the Outlook.com login page opens in a browser, sign in to your email account with the same credentials as you entered previously.

Note

If the Connect to Exchange email account dialog box repeatedly prompts you to sign in or you receive an error that you are unauthorized, Basic Auth may be disabled for accounts on your Microsoft 365 tenant. To test this add-in, try signing in again after setting the Use multi-factor auth property to True in the Web Add-in project properties dialog, or sign in using a Microsoft account instead.
In Outlook on the web, select or open a message.
Within the message, locate the ellipsis for the overflow menu containing the add-in's button.
Within the overflow menu, locate the add-in's button.
Click the button to open the add-in's task pane.

Note

If the task pane doesn't load, try to verify by opening it in a browser on the same machine.

Code samples

Outlook "Hello world" add-in: Learn how to build a simple Office Add-in with only a manifest, HTML web page, and a logo.

Next steps

Congratulations, you've successfully created your first Outlook task pane add-in! Next, learn more about developing Office Add-ins with Visual Studio.

Build your first Outlook add-in

Create the add-in

Prerequisites

Create the add-in project

Explore the project

Update the code

Try it out

Next steps

Prerequisites

Create the add-in project

Explore the Visual Studio solution

Update the code

Update the manifest

Try it out

Code samples

Next steps

See also

Feedback

Additional resources

Additional resources