diff --git a/inc/integrations/api/form-request-data.php b/inc/integrations/api/form-request-data.php
index 2431cb99b..503533eaa 100644
--- a/inc/integrations/api/form-request-data.php
+++ b/inc/integrations/api/form-request-data.php
@@ -108,7 +108,7 @@ class Form_Data_Request {
 	 * Constructor.
 	 *
 	 * @access  public
-	 * @param \WP_REST_Request|mixed $request Request Data.
+	 * @param \WP_REST_Request $request Request Data.
 	 * @since 2.0.3
 	 */
 	public function __construct( $request = null ) {
@@ -118,11 +118,21 @@ public function __construct( $request = null ) {
 		}
 
 		$this->request = $request;
-		$form_data     = $request->get_param( 'form_data' );
 
-		$form_data = json_decode( $form_data, true );
+		if ( ! empty( $request->get_param( 'form_data' ) ) ) {
+			$form_data          = $request->get_param( 'form_data' );
+			$form_data          = json_decode( $form_data, true );
+			$this->request_data = $this->sanitize_request_data( $form_data );
+		} else {
+			$body = json_decode( $request->get_body(), true );
+			if ( null !== $body ) {
+				$this->request_data = $this->sanitize_request_data( $body );
+			} else {
+				$this->error_code = Form_Data_Response::ERROR_MALFORMED_REQUEST;
+			}
+		}
+
 
-		$this->request_data = $this->sanitize_request_data( $form_data );
 		$this->form_options = new Form_Settings_Data( array() );
 	}
 
diff --git a/inc/integrations/api/form-response-data.php b/inc/integrations/api/form-response-data.php
index c2be56dae..bd45925ab 100644
--- a/inc/integrations/api/form-response-data.php
+++ b/inc/integrations/api/form-response-data.php
@@ -30,6 +30,7 @@ class Form_Data_Response {
 	const ERROR_MISSING_FILE_FIELD_OPTION         = '16';
 	const ERROR_AUTORESPONDER_MISSING_EMAIL_FIELD = '17';
 	const ERROR_AUTORESPONDER_COULD_NOT_SEND      = '18';
+	const ERROR_MALFORMED_REQUEST                 = '19';
 
 	// Request validation errors.
 	const ERROR_MISSING_DATA          = '101';
@@ -151,7 +152,7 @@ public function set_reasons( $reasons ) {
 
 	/**
 	 * Set success message.
-	 * 
+	 *
 	 * @param string $message The message.
 	 * @since 2.4
 	 */
@@ -356,6 +357,7 @@ public static function get_error_code_message( $error_code ) {
 			self::ERROR_AUTORESPONDER_MISSING_EMAIL_FIELD  => __( 'The email field is missing from the Form Block with Autoresponder activated.', 'otter-blocks' ),
 			self::ERROR_AUTORESPONDER_COULD_NOT_SEND       => __( 'The email from Autoresponder could not be sent.', 'otter-blocks' ),
 			self::ERROR_FILE_MISSING_BINARY                => __( 'The file data is missing.', 'otter-blocks' ),
+			self::ERROR_MALFORMED_REQUEST                  => __( 'The request is malformed.', 'otter-blocks' ),
 		);
 
 		if ( ! isset( $error_messages[ $error_code ] ) ) {
diff --git a/inc/integrations/class-form-utils.php b/inc/integrations/class-form-utils.php
index 86a1f6094..611308b9c 100644
--- a/inc/integrations/class-form-utils.php
+++ b/inc/integrations/class-form-utils.php
@@ -40,9 +40,14 @@ public static function generate_test_email() {
 			'eight',
 			'nine',
 			'ten',
+			'eleven',
+			'twelve',
+			'thirteen',
+			'fourteen',
+			'fifteen',
 		);
 
-		$name_1 = $words[ wp_rand( 0, count( $words ) ) ];
+		$name_1 = $words[ wp_rand( 0, count( $words ) - 1 ) ];
 		$name_2 = $words[ wp_rand( 2, count( $words ) ) - 1 ];
 
 		return "Otter-Form-successfully-connected.delete-on-confirmation.$name_1.$name_2@otter-blocks.com";
diff --git a/inc/integrations/interfaces/interface-form-subscribe-service.php b/inc/integrations/interfaces/interface-form-subscribe-service.php
index 8f3b482e9..d14785f0c 100644
--- a/inc/integrations/interfaces/interface-form-subscribe-service.php
+++ b/inc/integrations/interfaces/interface-form-subscribe-service.php
@@ -51,10 +51,10 @@ public function extract_data_from_integration( $wp_options_form );
 	public static function validate_api_key( $api_key );
 
 	/**
-	 * Test if the service is set up by registering a random email address on the contact list.
+	 * Make a request that add the email to the contact list.
 	 *
-	 * @return mixed
-	 * @since 2.0.3
+	 * @param string $email The email address.
+	 * @return array|\WP_Error The response from Mailchimp.
 	 */
-	public function test_subscription();
+	public function make_subscribe_request( $email );
 }
diff --git a/inc/integrations/providers/class-mailchimp.php b/inc/integrations/providers/class-mailchimp.php
index 80ffea446..88bab3def 100644
--- a/inc/integrations/providers/class-mailchimp.php
+++ b/inc/integrations/providers/class-mailchimp.php
@@ -111,7 +111,7 @@ function( $item ) {
 	 * @param string $email The email address.
 	 * @return array|\WP_Error The response from Mailchimp.
 	 */
-	private function make_subscribe_request( $email ) {
+	public function make_subscribe_request( $email ) {
 		$user_status = $this->get_new_user_status_mailchimp( $this->list_id );
 
 		$url = 'https://' . $this->server_name . '.api.mailchimp.com/3.0/lists/' . $this->list_id . '/members/' . md5( strtolower( $email ) );
@@ -161,23 +161,6 @@ public function subscribe( $form_data ) {
 		return $form_data;
 	}
 
-	/**
-	 * Test the subscription by registering a random generated email.
-	 *
-	 * @return Form_Data_Request
-	 * @since 2.0.3
-	 */
-	public function test_subscription() {
-		$req      = new Form_Data_Request();
-		$response = $this->make_subscribe_request( Form_Utils::generate_test_email() );
-
-		if ( is_wp_error( $response ) || 200 !== wp_remote_retrieve_response_code( $response ) ) {
-			$req->set_error( Form_Data_Response::get_error_code_message( Form_Data_Response::ERROR_PROVIDER_SUBSCRIBE_ERROR ) );
-		}
-
-		return $req;
-	}
-
 	/**
 	 * Set the API Key.
 	 *
diff --git a/inc/integrations/providers/class-sendinblue.php b/inc/integrations/providers/class-sendinblue.php
index 63f8a4cd3..267d4f0f1 100644
--- a/inc/integrations/providers/class-sendinblue.php
+++ b/inc/integrations/providers/class-sendinblue.php
@@ -154,22 +154,6 @@ public function subscribe( $form_data ) {
 		return $form_data;
 	}
 
-	/**
-	 * Test the subscription by registering a random generated email.
-	 *
-	 * @return Form_Data_Request
-	 */
-	public function test_subscription() {
-		$req      = new Form_Data_Request();
-		$response = $this->make_subscribe_request( Form_Utils::generate_test_email() );
-
-		if ( is_wp_error( $response ) || 400 === wp_remote_retrieve_response_code( $response ) ) {
-			$req->set_error( Form_Data_Response::get_error_code_message( Form_Data_Response::ERROR_PROVIDER_SUBSCRIBE_ERROR ) );
-		}
-
-		return $req;
-	}
-
 	/**
 	 * Set the API Key
 	 *
diff --git a/inc/server/class-form-server.php b/inc/server/class-form-server.php
index a5f351685..b2c940a5e 100644
--- a/inc/server/class-form-server.php
+++ b/inc/server/class-form-server.php
@@ -199,7 +199,7 @@ public function register_routes() {
 	 * @since 2.0.3
 	 */
 	public function editor( $request ) {
-		$data = new Form_Data_Request( json_decode( $request->get_body(), true ) );
+		$data = new Form_Data_Request( $request );
 		$res  = new Form_Data_Response();
 
 		$form_options = Form_Settings_Data::get_form_setting_from_wordpress_options( $data->get_payload_field( 'formOption' ) );
@@ -212,6 +212,10 @@ public function editor( $request ) {
 		}
 		$provider_handlers = Form_Providers::$instance->get_provider_handlers( $provider, 'editor' );
 
+		if ( $data->has_error() ) {
+			return $res->set_code( $data->get_error_code() )->build_response();
+		}
+
 		if ( $provider_handlers && Form_Providers::provider_has_handler( $provider_handlers, $data->get( 'handler' ) ) ) {
 			// Send the data to the provider.
 			return $provider_handlers[ $data->get( 'handler' ) ]( $data );
@@ -651,7 +655,13 @@ public function test_subscription_service( $form_data ) {
 				if ( $valid_api_key['valid'] ) {
 					if ( $form_options->has_list_id() ) {
 						$service->set_api_key( $form_options->get_api_key() )->set_list_id( $form_options->get_list_id() );
-						$res = $service->test_subscription();
+						$response = $service->make_subscribe_request( Form_Utils::generate_test_email() );
+
+						if ( is_wp_error( $response ) ) {
+							$res->set_error( Form_Data_Response::ERROR_RUNTIME_ERROR, $response->get_error_message() );
+						} else {
+							$res->mark_as_success();
+						}
 					} else {
 						$res->set_error( __( 'Contact list ID is missing!', 'otter-blocks' ) );
 					}
diff --git a/src/blocks/blocks/form/edit.js b/src/blocks/blocks/form/edit.js
index b9d029969..c81f35d06 100644
--- a/src/blocks/blocks/form/edit.js
+++ b/src/blocks/blocks/form/edit.js
@@ -553,7 +553,7 @@ const Edit = ({
 					} else {
 						createNotice(
 							'error',
-							res?.error,
+							res?.error ?? res?.reasons?.join( '. ' ) ?? __( 'An error has occurred.', 'otter-blocks' ),
 							{
 								isDismissible: true,
 								type: 'snackbar',
diff --git a/src/blocks/test/e2e/blocks/form.spec.js b/src/blocks/test/e2e/blocks/form.spec.js
index e8805aede..c897f50a6 100644
--- a/src/blocks/test/e2e/blocks/form.spec.js
+++ b/src/blocks/test/e2e/blocks/form.spec.js
@@ -273,4 +273,26 @@ test.describe( 'Form Block', () => {
 		// check for a element with the attribute data-redirect-url
 		await expect( await page.$( `[data-redirect="${REDIRECT_URL}"]` ) ).toBeTruthy();
 	});
+
+	test( 'errors on invalid API Key for Market Integration', async({ page, editor, browser }) => {
+
+		await editor.insertBlock({ name: 'themeisle-blocks/form' });
+
+		let formBlock = ( await editor.getBlocks() ).find( ( block ) => 'themeisle-blocks/form' === block.name );
+
+		expect( formBlock ).toBeTruthy();
+
+		const { clientId } = formBlock;
+
+		await page.click( `#block-${clientId} > div > fieldset > ul > li:nth-child(1) > button` );
+
+		await page.getByRole( 'button', { name: 'Marketing Integration' }).click();
+
+		// Select the Mailchimp option on the select with label Provider
+		await page.getByLabel( 'Provider' ).selectOption( 'mailchimp' );
+
+		await page.getByLabel( 'API Key' ).fill( 'invalid-api-key' );
+
+		await expect( page.getByLabel( 'Dismiss this notice' ) ).toBeVisible();
+	});
 });