New Outlook Custom Forms: Replace forms with web apps or Classic Outlook

Custom forms in Outlook allow you to create tailored interfaces for tasks, contacts, or mail items. The new Outlook for Windows no longer supports the custom form engine that Classic Outlook uses. This means any form you built with the Outlook Forms Designer will not open in the new client. This article explains why custom forms fail in new Outlook and shows you two paths forward: rebuilding forms as web apps or switching back to Classic Outlook.

Why New Outlook Drops Custom Form Support

New Outlook is built on a web-based platform that uses the same code as Outlook on the web and Outlook.com. This architecture does not include the Outlook Forms Designer or the VBScript runtime that powers custom forms. Microsoft chose this design to improve security, reduce complexity, and deliver updates faster. The trade-off is that any custom form created with the classic Forms Designer will not render in new Outlook. Instead, the item opens as a standard message or contact form with no custom fields or layout.

Classic Outlook stores form definitions in the Organizational Forms Library, Personal Forms Library, or in the folder itself. New Outlook cannot read these form definitions. It also cannot run the VBScript code that many forms use to validate data, show hidden fields, or automate actions. Even simple custom forms that only change the layout of standard fields will fail because new Outlook uses a fixed rendering engine.

What Happens to Existing Forms

If you open an item that was created with a custom form, new Outlook displays the default form for that item type. Any custom fields, tabs, buttons, or scripted behavior are hidden. The original data stored in custom properties remains in the item, but you cannot see or edit those fields without switching to Classic Outlook or using a web-based alternative that reads the same data source.

Option 1: Replace Custom Forms with Web Apps

For organizations that want to stay in new Outlook, the recommended approach is to replace custom forms with web applications. A web app can replicate the form layout, validation logic, and data storage that your custom form provided. The web app runs in a browser, so it works on any device and does not depend on the Outlook client version.

Using Power Apps to Build a Replacement Form

1. Open Power Apps in Microsoft 365
   Go to make.powerapps.com and sign in with your work or school account. Select Create from the left navigation panel.
2. Create a new canvas app
   Choose Canvas app from blank or start from a template. Give the app a name that matches the original Outlook form purpose, such as Expense Report or Contact Request.
3. Connect to your data source
   Use SharePoint, Microsoft Lists, Dataverse, or SQL Server to store the data that the form collects. Select Data in the left panel and add your data source. Map each field from the original form to a column in the data source.
4. Design the form layout
   Drag Text Input, Dropdown, Date Picker, and other controls onto the canvas. Arrange them in the same order as the original Outlook form. Set the DisplayMode property to Edit for data entry or View for read-only access.
5. Add validation logic
   Use Power Apps formulas to check required fields, format phone numbers, or calculate totals. For example, set the Visible property of a submit button to If(TextInput1.Text = “”, false, true).
6. Publish and share the app
   Select File > Save > Publish to SharePoint. Copy the app URL and share it with users. Add the URL to a SharePoint page or embed it in a Teams tab so users can find it easily.

Using SharePoint List Forms

1. Create a SharePoint list
   Go to your SharePoint site, select New > List, and choose Blank list. Give the list a name that matches the original form purpose.
2. Add columns that match the custom form fields
   Select Add column and choose the correct type: Single line of text, Choice, Currency, Date and Time, or Person or Group. Add all fields that appeared on the original Outlook form.
3. Customize the list form with Power Apps
   Open the list, select Integrate > Power Apps > Customize forms. Power Apps opens a pre-built form that matches your columns. Drag fields to rearrange them, add sections, and set validation rules.
4. Publish the customized form
   Select File > Publish to SharePoint. The form now replaces the default SharePoint list form. Users can open the list and select New to fill out the form.

Option 2: Switch Back to Classic Outlook

If you have many custom forms that would take weeks to rebuild, switching to Classic Outlook is the fastest solution. Classic Outlook runs on the same computer as new Outlook, and you can switch between them without uninstalling the other. Your custom forms, VBScript code, and COM add-ins will work exactly as before.

How to Switch from New Outlook to Classic Outlook

1. Open new Outlook
   Launch the new Outlook app from the Start menu or taskbar.
2. Go to File > Options > General
   In the left panel, select General. Scroll to the bottom of the General settings page.
3. Toggle the switch to Classic Outlook
   Locate the setting labeled Switch to Classic Outlook. Click the toggle to enable it. Outlook will prompt you to confirm the switch.
4. Restart Outlook
   Close and reopen Outlook. The classic interface loads with the ribbon, folder pane, and all custom form functionality restored.

If Custom Forms Still Do Not Work After Switching

Forms Are Not Published to the Correct Library

Classic Outlook loads custom forms from the Organizational Forms Library, the Personal Forms Library, or the folder-level form definition. If the form was published only to the Personal Forms Library on a different computer, it will not appear on your current machine. Open Classic Outlook, go to Tools > Options > Mail > Forms, and click Manage Forms to check which forms are available. If the form is missing, re-publish it from the original computer or export the form file (.oft) and import it.

VBScript Errors When Opening a Form

If a custom form runs VBScript code that references a COM add-in or a specific Outlook object model call, the script may fail after switching back. This usually happens when the add-in was uninstalled or disabled. Open Classic Outlook, go to File > Options > Add-ins, and ensure the required COM add-in is enabled. If the add-in is missing, reinstall it from the original source.

Custom Fields Appear Blank in the Form

Items created in new Outlook before switching back may have custom properties stored, but the form layout does not display them. This happens because new Outlook stripped the form definition from the item when it was created. To recover the data, open the item in Classic Outlook and use the Field Chooser to add the custom fields back to the form. Then save and republish the form to the folder.

New Outlook vs Classic Outlook for Custom Forms: Key Differences

Item	New Outlook	Classic Outlook
Custom Forms Designer	Not available	Available in Developer tab
VBScript support	Not supported	Full support
COM add-in support	Not supported	Full support
Form publishing	Not supported	Organizational and Personal Forms Libraries
Web-based replacement	Power Apps or SharePoint list forms	Not required
Security model	Restricted, no script execution	Configurable with Group Policy

You now have two clear options for handling custom forms in new Outlook. You can rebuild them as web apps using Power Apps or SharePoint lists, which gives you a modern interface that works on any device. Or you can switch back to Classic Outlook to keep your existing forms running without changes. If you choose the web app path, start by mapping each form field to a SharePoint column, then customize the form in Power Apps. If you stay with Classic Outlook, use the File > Options > General toggle to switch back and verify that your forms are published to the correct library.