---
title: Implement actors
slug: cms-12/docs/implementing-a-customized-actor
createdAt: 2026-08-10T15:56:04.000Z
---

:::hint{type="info"}
**Note**
[Optimizely Forms](docId:3SbSlJZIS_3iFmghfQA3J) is only supported by MVC-based websites and HTML5-compliant browsers.
:::

## Optimizely Forms actors

After a visitor submits a form, `Forms.Core` calls actors to perform additional processing on the server.

- You can extend and plug in the actor, and a third-party developer can implement it.
- You can run Actors in a sync or async manner.
- Each actor is provided with several data, including `SubmissionData` and the `HttpRequest`.
- Sync-actor can have (and can modify) the `HttpResponse`, so the actor can modify the response and cookie before returning the result to a visitor's browser.

By default, Optimizely Forms has two built-in Actors:

- `CallWebhookAfterSubmissionActor`
- `SendEmailAfterSubmissionActor`

### Handle submission actor's result

From version 4.16.0, you can let actors:

- Return a signal to cancel a form submission when an actor fails.
- Return an error message to be displayed to visitors.

To be able to cancel form submissions and to display error messages, you need to implement the following changes:

1. Actors must implement `ISyncOrderedSubmissionActor`. Actors implementing this interface run synchronously in ascending order, regardless of the `IsSyncedWithSubmissionProcess` value. (Actors are forced to run synchronously because you cannot control the result of async actors).
2. Actors must return an object instance of a class that implements `EPiServer.Forms.Core.PostSubmissionActor.Internal.ISubmissionActorResult`.
   By implementing this interface, the returned result will have two properties:
   \- `CancelSubmit` (boolean): determines whether the form submission should be canceled.
   \- `ErrorMessage` (string): this error message is displayed to visitors.

## Implement customized actors

Third-party developers can implement their actor by:

- Inheriting a `PostSubmissionActorBase` base class.
- Starting from scratch with the `IPostSubmissionActor` interface and interface `IUIPropertyCustomCollection` for edit view user interface of configuring the Actor model.

See the sample code for implementing an actor in the open-source project on [GitHub](https://github.com/episerver/EPiServer.Forms.Demo/tree/master/Implementation/Actors).