diff --git a/src/Api/Domain.php b/src/Api/Domain.php
index 1ad98169..7694f8f2 100644
--- a/src/Api/Domain.php
+++ b/src/Api/Domain.php
@@ -43,31 +43,19 @@ class Domain extends HttpApi
 {
     private const DKIM_SIZES = ['1024', '2048'];
 
-    /**
-     * Returns a list of domains on the account.
-     * @param array $params
-     * @param array $requestHeaders
-     * @return IndexResponse|array
-     * @throws ClientExceptionInterface
-     */
-    public function index(array $params = [], array $requestHeaders = [])
+    public function index(int $limit = 100, int $skip = 0, array $params = [], array $requestHeaders = [])
     {
-        $params = array_merge([
-            'limit' => 100,
-            'skip' => 0,
-        ], $params);
-
-        if (isset($params['limit'])) {
-            Assert::range($params['limit'], 1, 1000, 'Limit must be between 1 and 1000');
+        if ($limit) {
+            Assert::range($limit, 1, 1000, 'Limit must be between 1 and 1000');
         }
 
-        if (isset($params['skip'])) {
-            Assert::greaterThanEq($params['skip'], 0, 'Skip must be non-negative');
+        if ($skip) {
+            Assert::greaterThanEq($skip, 0, 'Skip must be non-negative');
         }
 
         if (isset($params['state'])) {
             Assert::oneOf($params['state'], ['active', 'unverified', 'disabled'],
-            'State must be one of: active, unverified, disabled');
+                'State must be one of: active, unverified, disabled');
         }
 
         if (isset($params['sort'])) {
@@ -75,11 +63,16 @@ public function index(array $params = [], array $requestHeaders = [])
                 'Sort must be one of: name, name:asc, name:desc');
         }
 
-        $params = array_filter($params, function ($value) {
+        $requestParams = array_merge([
+            'limit' => $limit,
+            'skip' => $skip,
+        ], $params);
+
+        $requestParams = array_filter($requestParams, function ($value) {
             return !is_null($value) && $value !== '';
         });
 
-        $response = $this->httpGet('/v3/domains', $params, $requestHeaders);
+        $response = $this->httpGet('/v3/domains', $requestParams, $requestHeaders);
 
         return $this->hydrateResponse($response, IndexResponse::class);
     }
diff --git a/src/Api/DomainV4.php b/src/Api/DomainV4.php
index 29c8bc07..a9fb3121 100644
--- a/src/Api/DomainV4.php
+++ b/src/Api/DomainV4.php
@@ -43,24 +43,22 @@ class DomainV4 extends HttpApi
     /**
      * Returns a list of domains on the account.
      * @link https://documentation.mailgun.com/docs/mailgun/api-reference/send/mailgun/domains/get-v4-domains#domains/get-v4-domains/request
+     * @param int $limit
+     * @param int $skip
      * @param array $params
      * @param array $requestHeaders
      * @return IndexResponse|array
      * @throws ClientExceptionInterface
+     * @throws \JsonException
      */
-    public function index(array $params = [], array $requestHeaders = [])
+    public function index(int $limit = 100, int $skip = 0, array $params = [], array $requestHeaders = [])
     {
-        $params = array_merge([
-            'limit' => 100,
-            'skip' => 0,
-        ], $params);
-
-        if (isset($params['limit'])) {
-            Assert::range($params['limit'], 1, 1000, 'Limit must be between 1 and 1000');
+        if ($limit) {
+            Assert::range($limit, 1, 1000, 'Limit must be between 1 and 1000');
         }
 
-        if (isset($params['skip'])) {
-            Assert::greaterThanEq($params['skip'], 0, 'Skip must be non-negative');
+        if ($skip) {
+            Assert::greaterThanEq($skip, 0, 'Skip must be non-negative');
         }
 
         if (isset($params['state'])) {
@@ -73,11 +71,16 @@ public function index(array $params = [], array $requestHeaders = [])
                 'Sort must be one of: name, name:asc, name:desc');
         }
 
-        $params = array_filter($params, function ($value) {
+        $requestParams = array_merge([
+            'limit' => $limit,
+            'skip' => $skip,
+        ], $params);
+
+        $requestParams = array_filter($requestParams, function ($value) {
             return !is_null($value) && $value !== '';
         });
 
-        $response = $this->httpGet('/v4/domains', $params, $requestHeaders);
+        $response = $this->httpGet('/v4/domains', $requestParams, $requestHeaders);
 
         return $this->hydrateResponse($response, IndexResponse::class);
     }
diff --git a/src/Api/Webhook.php b/src/Api/Webhook.php
index 98d524cb..814e95c3 100644
--- a/src/Api/Webhook.php
+++ b/src/Api/Webhook.php
@@ -30,18 +30,15 @@
  */
 class Webhook extends HttpApi
 {
-    /**
-     * @var string
-     */
-    private string $signingKey;
+    private ?string $signingKey;
 
     /**
      * @param ClientInterface $httpClient
-     * @param RequestBuilder  $requestBuilder
-     * @param Hydrator        $hydrator
-     * @param string          $signingKey
+     * @param RequestBuilder $requestBuilder
+     * @param Hydrator $hydrator
+     * @param string|null $signingKey
      */
-    public function __construct($httpClient, RequestBuilder $requestBuilder, Hydrator $hydrator, string $signingKey)
+    public function __construct($httpClient, RequestBuilder $requestBuilder, Hydrator $hydrator, ?string $signingKey)
     {
         parent::__construct($httpClient, $requestBuilder, $hydrator);
         $this->signingKey = $signingKey;
diff --git a/tests/Api/DomainV4Test.php b/tests/Api/DomainV4Test.php
new file mode 100644
index 00000000..cc284bfc
--- /dev/null
+++ b/tests/Api/DomainV4Test.php
@@ -0,0 +1,724 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * Copyright (C) 2013 Mailgun
+ *
+ * This software may be modified and distributed under the terms
+ * of the MIT license. See the LICENSE file for details.
+ */
+
+namespace Mailgun\Tests\Api;
+
+use Mailgun\Api\DomainV4;
+use Mailgun\Exception\InvalidArgumentException;
+use Mailgun\Model\Domain\ConnectionResponse;
+use Mailgun\Model\Domain\CreateCredentialResponse;
+use Mailgun\Model\Domain\CreateResponse;
+use Mailgun\Model\Domain\CredentialResponse;
+use Mailgun\Model\Domain\DeleteCredentialResponse;
+use Mailgun\Model\Domain\DeleteResponse;
+use Mailgun\Model\Domain\IndexResponse;
+use Mailgun\Model\Domain\ShowResponse;
+use Mailgun\Model\Domain\TrackingResponse;
+use Mailgun\Model\Domain\UpdateClickTrackingResponse;
+use Mailgun\Model\Domain\UpdateConnectionResponse;
+use Mailgun\Model\Domain\UpdateCredentialResponse;
+use Mailgun\Model\Domain\UpdateOpenTrackingResponse;
+use Mailgun\Model\Domain\UpdateUnsubscribeTrackingResponse;
+use Mailgun\Model\Domain\UseAutomaticSenderSecurity;
+use Mailgun\Model\Domain\VerifyResponse;
+use Mailgun\Model\Domain\WebPrefixResponse;
+use Mailgun\Model\Domain\WebSchemeResponse;
+use Nyholm\Psr7\Response;
+
+class DomainV4Test extends TestCase
+{
+    protected function getApiClass()
+    {
+        return DomainV4::class;
+    }
+
+    public function testIndex()
+    {
+        $this->setRequestMethod('GET');
+        $this->setRequestUri('/v4/domains?limit=100&skip=0');
+        $this->setHttpResponse(
+            new Response(
+                200, ['Content-Type' => 'application/json'], <<<'JSON'
+{
+  "total_count": 2,
+  "items": [
+    {
+      "created_at": "Wed, 10 Jul 2013 19:26:52 GMT",
+      "name": "samples.mailgun.org",
+      "state": "active",
+      "web_scheme": "http"
+    },
+    {
+      "created_at": "Thu, 11 Jul 2013 10:15:32 GMT",
+      "name": "test.mailgun.org",
+      "state": "unverified",
+      "web_scheme": "https"
+    }
+  ]
+}
+JSON
+            )
+        );
+
+        $api = $this->getApiInstance();
+        /**
+         * @var IndexResponse $response
+         */
+        $response = $api->index();
+        $this->assertInstanceOf(IndexResponse::class, $response);
+        $this->assertEquals(2, $response->getTotalCount());
+        $this->assertEquals('samples.mailgun.org', $response->getDomains()[0]->getName());
+    }
+
+    public function testIndexWithCustomParams()
+    {
+        $this->setRequestMethod('GET');
+        $this->setRequestUri('/v4/domains?limit=50&skip=10&state=active&sort=name%3Aasc');
+        $this->setHydrateClass(IndexResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->index(50, 10, ['state' => 'active', 'sort' => 'name:asc']);
+    }
+
+    public function testIndexLimitOutOfRangeException()
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        $api = $this->getApiInstance();
+        $api->index(1001);
+    }
+
+    public function testIndexInvalidStateException()
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        $api = $this->getApiInstance();
+        $api->index(100, 0, ['state' => 'invalid']);
+    }
+
+    public function testIndexInvalidSortException()
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        $api = $this->getApiInstance();
+        $api->index(100, 0, ['sort' => 'invalid']);
+    }
+
+    public function testShow()
+    {
+        $this->setRequestMethod('GET');
+        $this->setRequestUri('/v4/domains/example.com');
+        $this->setHydrateClass(ShowResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->show('example.com');
+    }
+
+    public function testCreate()
+    {
+        $this->setRequestMethod('POST');
+        $this->setRequestUri('/v4/domains');
+        $this->setRequestBody(
+            [
+                'name' => 'example.com',
+                'web_scheme' => 'http',
+                'dkim_key_size' => '1024',
+            ]
+        );
+        $this->setHydrateClass(CreateResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->create('example.com');
+    }
+
+    public function testCreateWithPassword()
+    {
+        $this->setRequestMethod('POST');
+        $this->setRequestUri('/v4/domains');
+        $this->setRequestBody(
+            [
+                'name' => 'example.com',
+                'smtp_password' => 'secret123',
+                'web_scheme' => 'http',
+                'dkim_key_size' => '1024',
+            ]
+        );
+        $this->setHydrateClass(CreateResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->create('example.com', 'secret123');
+    }
+
+    public function testCreateWithPasswordAndSpamAction()
+    {
+        $this->setRequestMethod('POST');
+        $this->setRequestUri('/v4/domains');
+        $this->setRequestBody(
+            [
+                'name' => 'example.com',
+                'smtp_password' => 'secret123',
+                'spam_action' => 'tag',
+                'web_scheme' => 'http',
+                'dkim_key_size' => '1024',
+            ]
+        );
+        $this->setHydrateClass(CreateResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->create('example.com', 'secret123', 'tag');
+    }
+
+    public function testCreateWithWildcard()
+    {
+        $this->setRequestMethod('POST');
+        $this->setRequestUri('/v4/domains');
+        $this->setRequestBody(
+            [
+                'name' => 'example.com',
+                'wildcard' => 'true',
+                'web_scheme' => 'http',
+                'dkim_key_size' => '1024',
+            ]
+        );
+        $this->setHydrateClass(CreateResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->create('example.com', null, null, true);
+    }
+
+    public function testCreateWithForceDkimAuthority()
+    {
+        $this->setRequestMethod('POST');
+        $this->setRequestUri('/v4/domains');
+        $this->setRequestBody(
+            [
+                'name' => 'example.com',
+                'force_dkim_authority' => 'true',
+                'web_scheme' => 'http',
+                'dkim_key_size' => '1024',
+            ]
+        );
+        $this->setHydrateClass(CreateResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->create('example.com', null, null, null, true);
+    }
+
+    public function testCreateWithIps()
+    {
+        $this->setRequestMethod('POST');
+        $this->setRequestUri('/v4/domains');
+        $this->setRequestBody(
+            [
+                'name' => 'example.com',
+                'ips' => '192.168.1.1,192.168.1.2',
+                'web_scheme' => 'http',
+                'dkim_key_size' => '1024',
+            ]
+        );
+        $this->setHydrateClass(CreateResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->create('example.com', null, null, null, null, ['192.168.1.1', '192.168.1.2']);
+    }
+
+    public function testCreateWithPoolId()
+    {
+        $this->setRequestMethod('POST');
+        $this->setRequestUri('/v4/domains');
+        $this->setRequestBody(
+            [
+                'name' => 'example.com',
+                'pool_id' => 'pool123',
+                'web_scheme' => 'http',
+                'dkim_key_size' => '1024',
+            ]
+        );
+        $this->setHydrateClass(CreateResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->create('example.com', null, null, null, null, null, 'pool123');
+    }
+
+    public function testCreateWithHttpsWebScheme()
+    {
+        $this->setRequestMethod('POST');
+        $this->setRequestUri('/v4/domains');
+        $this->setRequestBody(
+            [
+                'name' => 'example.com',
+                'web_scheme' => 'https',
+                'dkim_key_size' => '1024',
+            ]
+        );
+        $this->setHydrateClass(CreateResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->create('example.com', null, null, null, null, null, null, 'https');
+    }
+
+    public function testCreateWith2048DkimKeySize()
+    {
+        $this->setRequestMethod('POST');
+        $this->setRequestUri('/v4/domains');
+        $this->setRequestBody(
+            [
+                'name' => 'example.com',
+                'web_scheme' => 'http',
+                'dkim_key_size' => '2048',
+            ]
+        );
+        $this->setHydrateClass(CreateResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->create('example.com', null, null, null, null, null, null, 'http', '2048');
+    }
+
+    public function testCreateWithDkimHostName()
+    {
+        $this->setRequestMethod('POST');
+        $this->setRequestUri('/v4/domains');
+        $this->setRequestBody(
+            [
+                'name' => 'example.com',
+                'web_scheme' => 'http',
+                'dkim_key_size' => '1024',
+                'dkim_host_name' => 'dkim.example.com',
+            ]
+        );
+        $this->setHydrateClass(CreateResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->create('example.com', null, null, null, null, null, null, 'http', '1024', [], 'dkim.example.com');
+    }
+
+    public function testCreateWithDkimSelector()
+    {
+        $this->setRequestMethod('POST');
+        $this->setRequestUri('/v4/domains');
+        $this->setRequestBody(
+            [
+                'name' => 'example.com',
+                'web_scheme' => 'http',
+                'dkim_key_size' => '1024',
+                'dkim_selector' => 'selector1',
+            ]
+        );
+        $this->setHydrateClass(CreateResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->create('example.com', null, null, null, null, null, null, 'http', '1024', [], null, 'selector1');
+    }
+
+    public function testCreateWithUseAutomaticSenderSecurity()
+    {
+        $this->setRequestMethod('POST');
+        $this->setRequestUri('/v4/domains');
+        $this->setRequestBody(
+            [
+                'name' => 'example.com',
+                'web_scheme' => 'http',
+                'dkim_key_size' => '1024',
+                'use_automatic_sender_security' => 'true',
+            ]
+        );
+        $this->setHydrateClass(CreateResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->create('example.com', null, null, null, null, null, null, 'http', '1024', [], null, null, true);
+    }
+
+    public function testCreateInvalidDkimKeySizeException()
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        $api = $this->getApiInstance();
+        $api->create('example.com', null, null, null, null, null, null, 'http', '4096');
+    }
+
+    public function testCreateInvalidWebSchemeException()
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        $api = $this->getApiInstance();
+        $api->create('example.com', null, null, null, null, null, null, 'ftp');
+    }
+
+    public function testDelete()
+    {
+        $this->setRequestMethod('DELETE');
+        $this->setRequestUri('/v4/domains/example.com');
+        $this->setHydrateClass(DeleteResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->delete('example.com');
+    }
+
+    public function testCredentials()
+    {
+        $this->setRequestMethod('GET');
+        $this->setRequestUri('/v3/domains/example.com/credentials?limit=100&skip=0');
+        $this->setHydrateClass(CredentialResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->credentials('example.com');
+    }
+
+    public function testCredentialsWithCustomParams()
+    {
+        $this->setRequestMethod('GET');
+        $this->setRequestUri('/v3/domains/example.com/credentials?limit=50&skip=10');
+        $this->setHydrateClass(CredentialResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->credentials('example.com', 50, 10);
+    }
+
+    public function testCreateCredential()
+    {
+        $this->setRequestMethod('POST');
+        $this->setRequestUri('/v3/domains/example.com/credentials');
+        $this->setRequestBody(
+            [
+                'login' => 'testuser',
+                'password' => 'password123',
+            ]
+        );
+        $this->setHydrateClass(CreateCredentialResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->createCredential('example.com', 'testuser', 'password123');
+    }
+
+    public function testCreateCredentialPasswordTooShortException()
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        $api = $this->getApiInstance();
+        $api->createCredential('example.com', 'testuser', '1234');
+    }
+
+    public function testCreateCredentialPasswordTooLongException()
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        $api = $this->getApiInstance();
+        $api->createCredential('example.com', 'testuser', str_repeat('a', 33));
+    }
+
+    public function testUpdateCredential()
+    {
+        $this->setRequestMethod('PUT');
+        $this->setRequestUri('/v3/domains/example.com/credentials/testuser');
+        $this->setRequestBody(
+            [
+                'password' => 'newpassword',
+            ]
+        );
+        $this->setHydrateClass(UpdateCredentialResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->updateCredential('example.com', 'testuser', 'newpassword');
+    }
+
+    public function testUpdateCredentialPasswordTooShortException()
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        $api = $this->getApiInstance();
+        $api->updateCredential('example.com', 'testuser', '1234');
+    }
+
+    public function testDeleteCredential()
+    {
+        $this->setRequestMethod('DELETE');
+        $this->setRequestUri('/v3/domains/example.com/credentials/testuser');
+        $this->setHydrateClass(DeleteCredentialResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->deleteCredential('example.com', 'testuser');
+    }
+
+    public function testConnection()
+    {
+        $this->setRequestMethod('GET');
+        $this->setRequestUri('/v3/domains/example.com/connection');
+        $this->setHydrateClass(ConnectionResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->connection('example.com');
+    }
+
+    public function testUpdateConnection()
+    {
+        $this->setRequestMethod('PUT');
+        $this->setRequestUri('/v3/domains/example.com/connection');
+        $this->setRequestBody(
+            [
+                'require_tls' => 'true',
+                'skip_verification' => 'false',
+            ]
+        );
+        $this->setHydrateClass(UpdateConnectionResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->updateConnection('example.com', true, false);
+    }
+
+    public function testUpdateConnectionOnlyRequireTLS()
+    {
+        $this->setRequestMethod('PUT');
+        $this->setRequestUri('/v3/domains/example.com/connection');
+        $this->setRequestBody(
+            [
+                'require_tls' => 'false',
+            ]
+        );
+        $this->setHydrateClass(UpdateConnectionResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->updateConnection('example.com', false, null);
+    }
+
+    public function testUpdateConnectionOnlySkipVerification()
+    {
+        $this->setRequestMethod('PUT');
+        $this->setRequestUri('/v3/domains/example.com/connection');
+        $this->setRequestBody(
+            [
+                'skip_verification' => 'true',
+            ]
+        );
+        $this->setHydrateClass(UpdateConnectionResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->updateConnection('example.com', null, true);
+    }
+
+    public function testUpdateWebScheme()
+    {
+        $this->setRequestMethod('PUT');
+        $this->setRequestUri('/v4/domains/example.com');
+        $this->setRequestBody(
+            [
+                'web_scheme' => 'https',
+            ]
+        );
+        $this->setHydrateClass(WebSchemeResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->updateWebScheme('example.com', 'https');
+    }
+
+    public function testUpdateWebSchemeInvalidException()
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        $api = $this->getApiInstance();
+        $api->updateWebScheme('example.com', 'ftp');
+    }
+
+    public function testUpdateUseAutomaticSenderSecurity()
+    {
+        $this->setRequestMethod('PUT');
+        $this->setRequestUri('/v4/domains/example.com');
+        $this->setRequestBody(
+            [
+                'use_automatic_sender_security' => true,
+            ]
+        );
+        $this->setHydrateClass(UseAutomaticSenderSecurity::class);
+
+        $api = $this->getApiInstance();
+        $api->updateUseAutomaticSenderSecurity('example.com', true);
+    }
+
+    public function testUpdateUseAutomaticSenderSecurityFalse()
+    {
+        $this->setRequestMethod('PUT');
+        $this->setRequestUri('/v4/domains/example.com');
+        $this->setRequestBody(
+            [
+                'use_automatic_sender_security' => false,
+            ]
+        );
+        $this->setHydrateClass(UseAutomaticSenderSecurity::class);
+
+        $api = $this->getApiInstance();
+        $api->updateUseAutomaticSenderSecurity('example.com', false);
+    }
+
+    public function testVerify()
+    {
+        $this->setRequestMethod('PUT');
+        $this->setRequestUri('/v4/domains/example.com/verify');
+        $this->setHydrateClass(VerifyResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->verify('example.com');
+    }
+
+    public function testTracking()
+    {
+        $this->setRequestMethod('GET');
+        $this->setRequestUri('/v3/domains/example.com/tracking');
+        $this->setHydrateClass(TrackingResponse::class);
+
+        $api = $this->getApiInstance();
+        $api->tracking('example.com');
+    }
+
+    public function updateClickTrackingDataProvider(): array
+    {
+        return [
+            ['yes'],
+            ['no'],
+            ['htmlonly'],
+        ];
+    }
+
+    /**
+     * @dataProvider updateClickTrackingDataProvider
+     */
+    public function testUpdateClickTracking(string $active)
+    {
+        $this->setRequestMethod('PUT');
+        $this->setRequestUri('/v3/domains/example.com/tracking/click');
+        $this->setRequestBody(
+            [
+                'active' => $active,
+            ]
+        );
+        $this->setHydrateClass(UpdateClickTrackingResponse::class);
+
+        /**
+         * @var DomainV4
+         */
+        $api = $this->getApiInstance();
+        $api->updateClickTracking('example.com', $active);
+    }
+
+    public function testUpdateClickTrackingException()
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        /**
+         * @var DomainV4
+         */
+        $api = $this->getApiInstance();
+        $api->updateClickTracking('example.com', 'invalid');
+    }
+
+    public function updateOpenTrackingDataProvider(): array
+    {
+        return [
+            ['yes'],
+            ['no'],
+        ];
+    }
+
+    /**
+     * @dataProvider updateOpenTrackingDataProvider
+     */
+    public function testUpdateOpenTracking(string $active)
+    {
+        $this->setRequestMethod('PUT');
+        $this->setRequestUri('/v3/domains/example.com/tracking/open');
+        $this->setRequestBody(
+            [
+                'active' => $active,
+            ]
+        );
+        $this->setHydrateClass(UpdateOpenTrackingResponse::class);
+
+        /**
+         * @var DomainV4
+         */
+        $api = $this->getApiInstance();
+        $api->updateOpenTracking('example.com', $active);
+    }
+
+    public function testUpdateOpenTrackingException()
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        /**
+         * @var DomainV4
+         */
+        $api = $this->getApiInstance();
+        $api->updateOpenTracking('example.com', 'invalid');
+    }
+
+    public function unsubscribeDataProvider(): array
+    {
+        return [
+            ['yes', '<b>Unsubscribe</b>', 'Unsubscribe'],
+            ['no', '<s>Test</s>', 'Test'],
+            ['true', '<i>Footer</i>', 'Footer Text'],
+            ['false', '<u>HTML</u>', 'Plain Text'],
+        ];
+    }
+
+    /**
+     * @dataProvider unsubscribeDataProvider
+     */
+    public function testUpdateUnsubscribeTracking(string $active, string $htmlFooter, string $textFooter)
+    {
+        $expectedActive = (in_array($active, ['yes', 'true'], true)) ? 'true' : 'false';
+
+        $this->setRequestMethod('PUT');
+        $this->setRequestUri('/v3/domains/example.com/tracking/unsubscribe');
+        $this->setRequestBody(
+            [
+                'active' => $expectedActive,
+                'html_footer' => $htmlFooter,
+                'text_footer' => $textFooter,
+            ]
+        );
+        $this->setHydrateClass(UpdateUnsubscribeTrackingResponse::class);
+
+        /**
+         * @var DomainV4
+         */
+        $api = $this->getApiInstance();
+        $api->updateUnsubscribeTracking('example.com', $active, $htmlFooter, $textFooter);
+    }
+
+    public function testUpdateUnsubscribeTrackingException()
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        /**
+         * @var DomainV4
+         */
+        $api = $this->getApiInstance();
+        $api->updateUnsubscribeTracking('example.com', 'invalid', 'html-footer', 'text-footer');
+    }
+
+    public function testUpdateWebPrefix()
+    {
+        $this->setRequestMethod('PUT');
+        $this->setRequestUri('/v3/domains/example.com/web_prefix');
+        $this->setRequestBody(
+            [
+                'web_prefix' => 'tracking',
+            ]
+        );
+        $this->setHydrateClass(WebPrefixResponse::class);
+
+        /**
+         * @var DomainV4
+         */
+        $api = $this->getApiInstance();
+        $api->updateWebPrefix('example.com', 'tracking');
+    }
+}
+