diff --git a/src/Api/Domain.php b/src/Api/Domain.php
index 68d3585..2847113 100644
--- a/src/Api/Domain.php
+++ b/src/Api/Domain.php
@@ -325,13 +325,18 @@ class Domain extends HttpApi
      *
      * @param string $domain name of the domain
      *
-     * @param bool $active
+     * @param string $active
      * @return UpdateClickTrackingResponse|array|ResponseInterface
+     * @throws \Exception
      */
-    public function updateClickTracking(string $domain, bool $active)
+    public function updateClickTracking(string $domain, string $active)
     {
+        Assert::stringNotEmpty($domain);
+        Assert::stringNotEmpty($active);
+        Assert::oneOf($active, ['yes', 'no', 'htmlonly']);
+
         $params = [
-            'active' => $active ? 'true' : 'false',
+            'active' => $active,
         ];
 
         $response = $this->httpPut(sprintf('/v3/domains/%s/tracking/click', $domain), $params);
@@ -347,10 +352,14 @@ class Domain extends HttpApi
      *
      * @return UpdateOpenTrackingResponse|array|ResponseInterface
      */
-    public function updateOpenTracking(string $domain, bool $active)
+    public function updateOpenTracking(string $domain, string $active)
     {
+        Assert::stringNotEmpty($domain);
+        Assert::stringNotEmpty($active);
+        Assert::oneOf($active, ['yes', 'no']);
+
         $params = [
-            'active' => $active ? 'true' : 'false',
+            'active' => $active,
         ];
 
         $response = $this->httpPut(sprintf('/v3/domains/%s/tracking/open', $domain), $params);
@@ -362,15 +371,21 @@ class Domain extends HttpApi
      * Updates a domain unsubscribe tracking settings.
      *
      * @param string $domain name of the domain
-     * @param bool $active
+     * @param string $active
      * @param string $htmlFooter
-     * @param string $textFooter
+     * @param string|null $textFooter
      * @return UpdateUnsubscribeTrackingResponse|array|ResponseInterface
      */
-    public function updateUnsubscribeTracking(string $domain, bool $active, string $htmlFooter, string $textFooter)
+    public function updateUnsubscribeTracking(string $domain, string $active, string $htmlFooter, string $textFooter)
     {
+        Assert::stringNotEmpty($domain);
+        Assert::stringNotEmpty($active);
+        Assert::oneOf($active, ['yes', 'no', 'true', 'false']);
+        Assert::stringNotEmpty($htmlFooter);
+        Assert::nullOrString($textFooter);
+
         $params = [
-            'active' => $active ? 'true' : 'false',
+            'active' => (in_array($active, ['yes', 'true'])) ? 'true' : 'false',
             'html_footer' => $htmlFooter,
             'text_footer' => $textFooter,
         ];
diff --git a/src/Model/Domain/ClickTracking.php b/src/Model/Domain/ClickTracking.php
index 6101604..97825ad 100644
--- a/src/Model/Domain/ClickTracking.php
+++ b/src/Model/Domain/ClickTracking.php
@@ -23,7 +23,15 @@ final class ClickTracking
     public static function create(array $data): self
     {
         $model = new self();
-        $model->active = (bool) ($data['active'] ?? null);
+        $active = $data['active'] ?? null;
+
+        if (true === $active) {
+            $model->active = 'yes';
+        } elseif (false === $active) {
+            $model->active = 'no';
+        } else {
+            $model->active = $active;
+        }
 
         return $model;
     }
@@ -32,8 +40,18 @@ final class ClickTracking
     {
     }
 
-    public function isActive(): bool
+    public function getActive(): ?string
     {
         return $this->active;
     }
+
+    public function isActive(): bool
+    {
+        return $this->getActive() === 'yes';
+    }
+
+    public function isHtmlOnly(): bool
+    {
+        return $this->getActive() === 'htmlonly';
+    }
 }
diff --git a/src/Model/Domain/OpenTracking.php b/src/Model/Domain/OpenTracking.php
index a99febd..768863c 100644
--- a/src/Model/Domain/OpenTracking.php
+++ b/src/Model/Domain/OpenTracking.php
@@ -23,7 +23,15 @@ final class OpenTracking
     public static function create(array $data): self
     {
         $model = new self();
-        $model->active = (bool) ($data['active'] ?? null);
+        $active = $data['active'] ?? null;
+
+        if (true === $active) {
+            $model->active = 'yes';
+        } elseif (false === $active) {
+            $model->active = 'no';
+        } else {
+            $model->active = $active;
+        }
 
         return $model;
     }
@@ -32,8 +40,16 @@ final class OpenTracking
     {
     }
 
-    public function isActive(): bool
+    /**
+     * @return string
+     */
+    public function getActive(): ?string
     {
         return $this->active;
     }
+
+    public function isActive(): bool
+    {
+        return $this->getActive() === 'yes';
+    }
 }
diff --git a/src/Model/Domain/TrackingResponse.php b/src/Model/Domain/TrackingResponse.php
index 0f68805..9a3d204 100644
--- a/src/Model/Domain/TrackingResponse.php
+++ b/src/Model/Domain/TrackingResponse.php
@@ -32,7 +32,7 @@ final class TrackingResponse implements ApiResponse
 
         $model = new self();
         $model->click = ClickTracking::create($trackingSettings['click'] ?? []);
-        $model->open = OpenTracking::create($trackingSettings['click'] ?? []);
+        $model->open = OpenTracking::create($trackingSettings['open'] ?? []);
         $model->unsubscribe = UnsubscribeTracking::create($trackingSettings['unsubscribe'] ?? []);
 
         return $model;
diff --git a/src/Model/Domain/UnsubscribeTracking.php b/src/Model/Domain/UnsubscribeTracking.php
index e6c5d63..e2d510a 100644
--- a/src/Model/Domain/UnsubscribeTracking.php
+++ b/src/Model/Domain/UnsubscribeTracking.php
@@ -25,7 +25,7 @@ final class UnsubscribeTracking
     public static function create(array $data): self
     {
         $model = new self();
-        $model->active = (bool) ($data['active'] ?? null);
+        $model->active = ($data['active'] ?? null) ? 'true' : 'false';
         $model->htmlFooter = $data['html_footer'] ?? '';
         $model->textFooter = $data['text_footer'] ?? '';
 
@@ -37,6 +37,11 @@ final class UnsubscribeTracking
     }
 
     public function isActive(): bool
+    {
+        return $this->active === 'true';
+    }
+
+    public function getActive(): string
     {
         return $this->active;
     }
diff --git a/tests/Api/DomainTest.php b/tests/Api/DomainTest.php
index 42bd103..3ad4023 100644
--- a/tests/Api/DomainTest.php
+++ b/tests/Api/DomainTest.php
@@ -13,6 +13,7 @@ namespace Mailgun\Tests\Api;
 
 use GuzzleHttp\Psr7\Response;
 use Mailgun\Api\Domain;
+use Mailgun\Exception\InvalidArgumentException;
 use Mailgun\Model\Domain\ConnectionResponse;
 use Mailgun\Model\Domain\CreateCredentialResponse;
 use Mailgun\Model\Domain\CreateResponse;
@@ -274,23 +275,24 @@ JSON
         $api->tracking('example.com');
     }
 
-    public function activeInactiveDataProvider(): array
+    public function updateClickTrackingDataProvider(): array
     {
         return [
-            [true],
-            [false],
+            ['yes'],
+            ['no'],
+            ['htmlonly'],
         ];
     }
 
     /**
-     * @dataProvider activeInactiveDataProvider
+     * @dataProvider updateClickTrackingDataProvider
      */
-    public function testUpdateClickTracking(bool $isActive)
+    public function testUpdateClickTracking(string $active)
     {
         $this->setRequestMethod('PUT');
         $this->setRequestUri('/v3/domains/example.com/tracking/click');
         $this->setRequestBody([
-            'active' => $isActive ? 'true' : 'false',
+            'active' => $active,
         ]);
         $this->setHydrateClass(UpdateClickTrackingResponse::class);
 
@@ -298,18 +300,37 @@ JSON
          * @var $api Domain
          */
         $api = $this->getApiInstance();
-        $api->updateClickTracking('example.com', $isActive);
+        $api->updateClickTracking('example.com', $active);
+    }
+
+    public function testUpdateClickTrackingException()
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        /**
+         * @var $api Domain
+         */
+        $api = $this->getApiInstance();
+        $api->updateClickTracking('example.com', 'non-valid-active-param');
+    }
+
+    public function updateOpenTrackingDataProvider(): array
+    {
+        return [
+            ['yes'],
+            ['no'],
+        ];
     }
 
     /**
-     * @dataProvider activeInactiveDataProvider
+     * @dataProvider updateOpenTrackingDataProvider
      */
-    public function testUpdateOpenTracking(bool $isActive)
+    public function testUpdateOpenTracking(string $active)
     {
         $this->setRequestMethod('PUT');
         $this->setRequestUri('/v3/domains/example.com/tracking/open');
         $this->setRequestBody([
-            'active' => $isActive ? 'true' : 'false',
+            'active' => $active,
         ]);
         $this->setHydrateClass(UpdateOpenTrackingResponse::class);
 
@@ -317,29 +338,37 @@ JSON
          * @var $api Domain
          */
         $api = $this->getApiInstance();
-        $api->updateOpenTracking('example.com', $isActive);
+        $api->updateOpenTracking('example.com', $active);
+    }
+
+    public function testUpdateOpenTrackingException()
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        /**
+         * @var $api Domain
+         */
+        $api = $this->getApiInstance();
+        $api->updateOpenTracking('example.com', 'non-valid-active-param');
     }
 
     public function unsubscribeDataProvider(): array
     {
         return [
-            [true, '<b>Test</b>', 'Test1'],
-            [false, '<s>Test</s>', 'Test2'],
+            ['true', '<b>Test</b>', 'Test1'],
+            ['false', '<s>Test</s>', 'Test2'],
         ];
     }
 
     /**
      * @dataProvider unsubscribeDataProvider
-     * @param bool $isActive
-     * @param string $htmlFooter
-     * @param string $textFooter
      */
-    public function testUpdateUnsubscribeTracking(bool $isActive, string $htmlFooter, string $textFooter)
+    public function testUpdateUnsubscribeTracking(string $active, string $htmlFooter, string $textFooter)
     {
         $this->setRequestMethod('PUT');
         $this->setRequestUri('/v3/domains/example.com/tracking/unsubscribe');
         $this->setRequestBody([
-            'active' => $isActive ? 'true' : 'false',
+            'active' => $active,
             'html_footer' => $htmlFooter,
             'text_footer' => $textFooter,
         ]);
@@ -349,6 +378,17 @@ JSON
          * @var $api Domain
          */
         $api = $this->getApiInstance();
-        $api->updateUnsubscribeTracking('example.com', $isActive, $htmlFooter, $textFooter);
+        $api->updateUnsubscribeTracking('example.com', $active, $htmlFooter, $textFooter);
+    }
+
+    public function testUpdateUnsubscribeTrackingException()
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        /**
+         * @var $api Domain
+         */
+        $api = $this->getApiInstance();
+        $api->updateUnsubscribeTracking('example.com', 'non-valid-active-param', 'html-footer', 'text-footer');
     }
 }
diff --git a/tests/Model/Domain/TrackingResponseTest.php b/tests/Model/Domain/TrackingResponseTest.php
index 371c984..29a01bb 100644
--- a/tests/Model/Domain/TrackingResponseTest.php
+++ b/tests/Model/Domain/TrackingResponseTest.php
@@ -26,13 +26,13 @@ class TrackingResponseTest extends BaseModelTest
 {
     "tracking": {
         "click": {
-            "active": true
+            "active": "htmlonly"
         },
         "open": {
-            "active": true
+            "active": "no"
         },
         "unsubscribe": {
-            "active": true,
+            "active": false,
             "html_footer": "<s>Test<\/s>",
             "text_footer": "Test"
         }
@@ -42,15 +42,18 @@ JSON;
         $model = TrackingResponse::create(json_decode($json, true));
         $this->assertNotEmpty($model->getClick());
         $this->assertInstanceOf(ClickTracking::class, $model->getClick());
-        $this->assertTrue($model->getClick()->isActive());
+        $this->assertEquals('htmlonly', $model->getClick()->getActive());
+        $this->assertFalse($model->getClick()->isActive());
 
         $this->assertNotEmpty($model->getOpen());
         $this->assertInstanceOf(OpenTracking::class, $model->getOpen());
-        $this->assertTrue($model->getOpen()->isActive());
+        $this->assertEquals('no', $model->getOpen()->getActive());
+        $this->assertFalse($model->getOpen()->isActive());
 
         $this->assertNotEmpty($model->getUnsubscribe());
         $this->assertInstanceOf(UnsubscribeTracking::class, $model->getUnsubscribe());
-        $this->assertTrue($model->getUnsubscribe()->isActive());
+        $this->assertEquals('false', $model->getUnsubscribe()->getActive());
+        $this->assertFalse($model->getUnsubscribe()->isActive());
         $this->assertEquals('<s>Test</s>', $model->getUnsubscribe()->getHtmlFooter());
         $this->assertEquals('Test', $model->getUnsubscribe()->getTextFooter());
     }
diff --git a/tests/Model/Domain/UpdateClickTrackingResponseTest.php b/tests/Model/Domain/UpdateClickTrackingResponseTest.php
index 6aa27e0..335b6cc 100644
--- a/tests/Model/Domain/UpdateClickTrackingResponseTest.php
+++ b/tests/Model/Domain/UpdateClickTrackingResponseTest.php
@@ -23,7 +23,7 @@ class UpdateClickTrackingResponseTest extends BaseModelTest
             <<<'JSON'
 {
   "click": {
-    "active": true
+    "active": "htmlonly"
   },
   "message": "Domain tracking settings have been updated"
 }
@@ -33,6 +33,7 @@ JSON;
         $this->assertEquals('Domain tracking settings have been updated', $model->getMessage());
         $this->assertNotEmpty($model->getClick());
         $this->assertInstanceOf(ClickTracking::class, $model->getClick());
-        $this->assertTrue($model->getClick()->isActive());
+        $this->assertEquals('htmlonly', $model->getClick()->getActive());
+        $this->assertFalse($model->getClick()->isActive());
     }
 }
diff --git a/tests/Model/Domain/UpdateOpenTrackingResponseTest.php b/tests/Model/Domain/UpdateOpenTrackingResponseTest.php
index 6afd7c2..9fbdd6a 100644
--- a/tests/Model/Domain/UpdateOpenTrackingResponseTest.php
+++ b/tests/Model/Domain/UpdateOpenTrackingResponseTest.php
@@ -23,7 +23,7 @@ class UpdateOpenTrackingResponseTest extends BaseModelTest
             <<<'JSON'
 {
   "open": {
-    "active": true
+    "active": "no"
   },
   "message": "Domain tracking settings have been updated"
 }
@@ -33,6 +33,6 @@ JSON;
         $this->assertEquals('Domain tracking settings have been updated', $model->getMessage());
         $this->assertNotEmpty($model->getOpen());
         $this->assertInstanceOf(OpenTracking::class, $model->getOpen());
-        $this->assertTrue($model->getOpen()->isActive());
+        $this->assertFalse($model->getOpen()->isActive());
     }
 }