diff --git a/.circleci/config.yml b/.circleci/config.yml
index 847e337b..62770a37 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -5,14 +5,9 @@ version: 2.1
 workflows:
   php-tests:
     jobs:
-      - unit-tests:
-          name: php81
-          version: "8.1"
       - unit-tests:
           name: php82
           version: "8.2"
-          requires:
-            - php81
       - unit-tests:
           name: php83
           version: "8.3"
@@ -23,6 +18,11 @@ workflows:
           version: "8.4"
           requires:
             - php83
+      - unit-tests:
+          name: php85
+          version: "8.5"
+          requires:
+            - php84
 
 jobs:
   unit-tests:
diff --git a/composer.json b/composer.json
index 6a3cd734..88872815 100644
--- a/composer.json
+++ b/composer.json
@@ -9,7 +9,7 @@
   "license": "MIT",
   "description": "The officially supported client for Postmark (https://postmarkapp.com)",
   "require": {
-    "php": "~8.1 || ~8.2|| ~8.3 || ~8.4",
+    "php": "~8.2|| ~8.3 || ~8.4 || ~8.5",
     "guzzlehttp/guzzle": "^7.8"
   },
   "require-dev": {
diff --git a/src/Postmark/Models/PostmarkAttachment.php b/src/Postmark/Models/PostmarkAttachment.php
index 4d2ddf03..90a8368f 100644
--- a/src/Postmark/Models/PostmarkAttachment.php
+++ b/src/Postmark/Models/PostmarkAttachment.php
@@ -20,17 +20,17 @@ private function __construct($base64EncodedData, $attachmentName, $mimeType = 'a
         $this->contentId = $contentId;
     }
 
-    public static function fromRawData($data, $attachmentName, ?string $mimeType = null, ?string $contentId = null)
+    public static function fromRawData(string $data, string $attachmentName, ?string $mimeType = null, ?string $contentId = null): PostmarkAttachment
     {
         return new PostmarkAttachment(base64_encode($data), $attachmentName, $mimeType, $contentId);
     }
 
-    public static function fromBase64EncodedData($base64EncodedData, $attachmentName, ?string $mimeType = null, ?string $contentId = null)
+    public static function fromBase64EncodedData(string $base64EncodedData, string $attachmentName, ?string $mimeType = null, ?string $contentId = null): PostmarkAttachment
     {
         return new PostmarkAttachment($base64EncodedData, $attachmentName, $mimeType, $contentId);
     }
 
-    public static function fromFile($filePath, $attachmentName, ?string $mimeType = null, ?string $contentId = null)
+    public static function fromFile(string $filePath, string $attachmentName, ?string $mimeType = null, ?string $contentId = null): PostmarkAttachment
     {
         return new PostmarkAttachment(base64_encode(file_get_contents($filePath)), $attachmentName, $mimeType, $contentId);
     }
diff --git a/src/Postmark/Models/PostmarkBounceList.php b/src/Postmark/Models/PostmarkBounceList.php
index b2393b15..7a005b4c 100644
--- a/src/Postmark/Models/PostmarkBounceList.php
+++ b/src/Postmark/Models/PostmarkBounceList.php
@@ -11,7 +11,8 @@ public function __construct(array $values)
     {
         $this->TotalCount = !empty($values['TotalCount']) ? $values['TotalCount'] : 0;
         $tempBounce = [];
-        foreach ($values['Bounces'] as $bounce) {
+        $bounces = $values['Bounces'] ?? [];
+        foreach ($bounces as $bounce) {
             $obj = json_decode(json_encode($bounce));
             $postmarkBounce = new PostmarkBounce((array) $obj);
 
diff --git a/src/Postmark/Models/PostmarkInboundMessageList.php b/src/Postmark/Models/PostmarkInboundMessageList.php
index 27c39ed4..056c9a01 100644
--- a/src/Postmark/Models/PostmarkInboundMessageList.php
+++ b/src/Postmark/Models/PostmarkInboundMessageList.php
@@ -11,7 +11,8 @@ public function __construct(array $values)
     {
         $this->TotalCount = !empty($values['TotalCount']) ? $values['TotalCount'] : 0;
         $tempInboundMessages = [];
-        foreach ($values['InboundMessages'] as $message) {
+        $inboundMessages = $values['InboundMessages'] ?? [];
+        foreach ($inboundMessages as $message) {
             $obj = json_decode(json_encode($message));
             $postmarkMessage = new PostmarkInboundMessage((array) $obj);
 
diff --git a/src/Postmark/Models/PostmarkOpen.php b/src/Postmark/Models/PostmarkOpen.php
index 53c7dc8f..3fe61e0a 100644
--- a/src/Postmark/Models/PostmarkOpen.php
+++ b/src/Postmark/Models/PostmarkOpen.php
@@ -63,7 +63,7 @@ public function setUserAgent(string $UserAgent): PostmarkOpen
         return $this;
     }
 
-    public function getGeo(): PostmarkGeographyInfo
+    public function getGeo(): ?PostmarkGeographyInfo
     {
         return $this->Geo;
     }
@@ -114,7 +114,7 @@ public function setReceivedAt(string $ReceivedAt): PostmarkOpen
         return $this;
     }
 
-    public function getClient(): PostmarkAgentInfo
+    public function getClient(): ?PostmarkAgentInfo
     {
         return $this->Client;
     }
@@ -129,7 +129,7 @@ public function setClient(mixed $Client): PostmarkOpen
         return $this;
     }
 
-    public function getOS(): PostmarkAgentInfo
+    public function getOS(): ?PostmarkAgentInfo
     {
         return $this->OS;
     }
diff --git a/src/Postmark/Models/PostmarkOutboundMessageList.php b/src/Postmark/Models/PostmarkOutboundMessageList.php
index 4bb63ff3..71ba7822 100644
--- a/src/Postmark/Models/PostmarkOutboundMessageList.php
+++ b/src/Postmark/Models/PostmarkOutboundMessageList.php
@@ -11,7 +11,8 @@ public function __construct(array $values)
     {
         $this->TotalCount = !empty($values['TotalCount']) ? $values['TotalCount'] : 0;
         $tempMessages = [];
-        foreach ($values['Messages'] as $message) {
+        $messages = $values['Messages'] ?? [];
+        foreach ($messages as $message) {
             $obj = json_decode(json_encode($message));
             $postmarkMessage = new PostmarkOutboundMessage((array) $obj);
 
diff --git a/src/Postmark/Models/Suppressions/PostmarkSuppressionList.php b/src/Postmark/Models/Suppressions/PostmarkSuppressionList.php
index 193a79d7..7f4ef4f3 100644
--- a/src/Postmark/Models/Suppressions/PostmarkSuppressionList.php
+++ b/src/Postmark/Models/Suppressions/PostmarkSuppressionList.php
@@ -9,7 +9,8 @@ class PostmarkSuppressionList
     public function __construct(array $values)
     {
         $tempSuppressions = [];
-        foreach ($values['Suppressions'] as $sups) {
+        $suppressions = $values['Suppressions'] ?? [];
+        foreach ($suppressions as $sups) {
             $obj = json_decode(json_encode($sups));
             $postmarkSup = new PostmarkSuppression((array) $obj);
 
diff --git a/src/Postmark/Models/Suppressions/PostmarkSuppressionResultList.php b/src/Postmark/Models/Suppressions/PostmarkSuppressionResultList.php
index c2d77c36..87551569 100644
--- a/src/Postmark/Models/Suppressions/PostmarkSuppressionResultList.php
+++ b/src/Postmark/Models/Suppressions/PostmarkSuppressionResultList.php
@@ -9,7 +9,8 @@ class PostmarkSuppressionResultList
     public function __construct(array $values)
     {
         $tempSuppressions = [];
-        foreach ($values['Suppressions'] as $sups) {
+        $suppressions = $values['Suppressions'] ?? [];
+        foreach ($suppressions as $sups) {
             $obj = json_decode(json_encode($sups));
             $postmarkSup = new PostmarkSuppressionRequestResult((array) $obj);
 
diff --git a/src/Postmark/PostmarkClient.php b/src/Postmark/PostmarkClient.php
index 912d68ff..d579a057 100644
--- a/src/Postmark/PostmarkClient.php
+++ b/src/Postmark/PostmarkClient.php
@@ -306,7 +306,7 @@ public function getDeliveryStatistics(): PostmarkDeliveryStats
      * @param null|bool   $inactive      specifies if the bounce caused Postmark to deactivate this email
      * @param null|string $emailFilter   Filter by email address
      * @param null|string $tag           Filter by tag
-     * @param null|int    $messageID     Filter by MessageID
+     * @param null|string $messageID     Filter by MessageID
      * @param null|string $fromdate      filter for bounces after is date
      * @param null|string $todate        filter for bounces before this date
      * @param null|string $messagestream Filter by Message Stream ID. If null, the default "outbound" transactional stream will be used.
@@ -320,7 +320,7 @@ public function getBounces(
         ?bool $inactive = null,
         ?string $emailFilter = null,
         ?string $tag = null,
-        ?int $messageID = null,
+        ?string $messageID = null,
         ?string $fromdate = null,
         ?string $todate = null,
         ?string $messagestream = null
diff --git a/tests/PostmarkClientBounceTest.php b/tests/PostmarkClientBounceTest.php
index d98fa0fc..cab198b1 100644
--- a/tests/PostmarkClientBounceTest.php
+++ b/tests/PostmarkClientBounceTest.php
@@ -18,6 +18,48 @@ public static function setUpBeforeClass(): void
         PostmarkClientSuppressionsTest::tearDownAfterClass();
     }
 
+    /**
+     * @depends testClientCanActivateBounce
+     */
+    public function testClientCanGetBounce()
+    {
+        $tk = parent::$testKeys;
+        $client = new PostmarkClient($tk->READ_SELENIUM_TEST_SERVER_TOKEN, $tk->TEST_TIMEOUT);
+        $bounces = $client->getBounces(10, 0);
+        $bounceList = $bounces->getBounces();
+        
+        if (empty($bounceList)) {
+            $this->markTestSkipped('No bounces available for testing');
+            return;
+        }
+        
+        $id = $bounceList[0]->getID();
+        $bounce = $client->getBounce($id);
+        $this->assertNotEmpty($bounce);
+        $this->assertEquals($id, $bounce->getID());
+    }
+
+    /**
+     * @depends testClientCanActivateBounce
+     */
+    public function testClientCanGetBounceDump()
+    {
+        $tk = parent::$testKeys;
+        $client = new PostmarkClient($tk->READ_SELENIUM_TEST_SERVER_TOKEN, $tk->TEST_TIMEOUT);
+        $bounces = $client->getBounces(10, 0);
+        $bounceList = $bounces->getBounces();
+        
+        if (empty($bounceList)) {
+            $this->markTestSkipped('No bounces available for testing');
+            return;
+        }
+        
+        $id = $bounceList[0]->getID();
+        $dump = $client->getBounceDump($id);
+        $this->assertNotEmpty($dump);
+        $this->assertNotEmpty($dump->getBody());
+    }
+    
     public function testClientCanActivateBounce()
     {
         $tk = parent::$testKeys;
@@ -105,32 +147,5 @@ public function testClientCanGetBounces()
         $bounces = $client->getBounces(10, 0);
         $this->assertNotEmpty($bounces);
     }
-
-    /**
-     * @depends testClientCanActivateBounce
-     */
-    public function testClientCanGetBounce()
-    {
-        $tk = parent::$testKeys;
-        $client = new PostmarkClient($tk->READ_SELENIUM_TEST_SERVER_TOKEN, $tk->TEST_TIMEOUT);
-        $bounces = $client->getBounces(10, 0);
-        $id = $bounces->getBounces()[0]->getID();
-        $bounce = $client->getBounce($id);
-        $this->assertNotEmpty($bounce);
-        $this->assertEquals($id, $bounce->getID());
-    }
-
-    /**
-     * @depends testClientCanActivateBounce
-     */
-    public function testClientCanGetBounceDump()
-    {
-        $tk = parent::$testKeys;
-        $client = new PostmarkClient($tk->READ_SELENIUM_TEST_SERVER_TOKEN, $tk->TEST_TIMEOUT);
-        $bounces = $client->getBounces(10, 0);
-        $id = $bounces->Bounces[0]->getID();
-        $dump = $client->getBounceDump($id);
-        $this->assertNotEmpty($dump);
-        $this->assertNotEmpty($dump->getBody());
-    }
+    
 }
diff --git a/tests/PostmarkClientInboundMessageTest.php b/tests/PostmarkClientInboundMessageTest.php
index da8f8405..50283863 100644
--- a/tests/PostmarkClientInboundMessageTest.php
+++ b/tests/PostmarkClientInboundMessageTest.php
@@ -30,7 +30,14 @@ public function testClientCanGetInboundMessageDetails()
         $client = new PostmarkClient($tk->READ_SELENIUM_TEST_SERVER_TOKEN, $tk->TEST_TIMEOUT);
 
         $retrievedMessages = $client->getInboundMessages(10);
-        $baseMessageId = $retrievedMessages->getInboundMessages()[0]->getMessageID();
+        $inboundMessages = $retrievedMessages->getInboundMessages();
+        
+        if (empty($inboundMessages)) {
+            $this->markTestSkipped('No inbound messages available for testing');
+            return;
+        }
+        
+        $baseMessageId = $inboundMessages[0]->getMessageID();
         $message = $client->getInboundMessageDetails($baseMessageId);
 
         $this->assertNotEmpty($message);
diff --git a/tests/PostmarkClientOutboundMessageTest.php b/tests/PostmarkClientOutboundMessageTest.php
index d35cee68..78c39ede 100644
--- a/tests/PostmarkClientOutboundMessageTest.php
+++ b/tests/PostmarkClientOutboundMessageTest.php
@@ -29,8 +29,14 @@ public function testClientCanGetOutboundMessageDetails()
         $client = new PostmarkClient($tk->READ_SELENIUM_TEST_SERVER_TOKEN, $tk->TEST_TIMEOUT);
 
         $retrievedMessages = $client->getOutboundMessages(1, 50);
-
-        $baseMessageId = $retrievedMessages->getMessages()[0]->getMessageID();
+        $messages = $retrievedMessages->getMessages();
+        
+        if (empty($messages)) {
+            $this->markTestSkipped('No outbound messages available for testing');
+            return;
+        }
+
+        $baseMessageId = $messages[0]->getMessageID();
         $message = $client->getOutboundMessageDetails($baseMessageId);
 
         $this->assertNotEmpty($message);
@@ -42,7 +48,14 @@ public function testClientCanGetOutboundMessageDump()
         $client = new PostmarkClient($tk->READ_SELENIUM_TEST_SERVER_TOKEN, $tk->TEST_TIMEOUT);
 
         $retrievedMessages = $client->getOutboundMessages(1, 50);
-        $baseMessageId = $retrievedMessages->getMessages()[0]->getMessageID();
+        $messages = $retrievedMessages->getMessages();
+        
+        if (empty($messages)) {
+            $this->markTestSkipped('No outbound messages available for testing');
+            return;
+        }
+        
+        $baseMessageId = $messages[0]->getMessageID();
         $message = $client->getOutboundMessageDump($baseMessageId);
 
         $this->assertNotEmpty($message);
diff --git a/tests/PostmarkClientSuppressionsTest.php b/tests/PostmarkClientSuppressionsTest.php
index 894b1032..a08ad588 100644
--- a/tests/PostmarkClientSuppressionsTest.php
+++ b/tests/PostmarkClientSuppressionsTest.php
@@ -21,11 +21,18 @@ public static function tearDownAfterClass(): void
         $client = new PostmarkClient($tk->WRITE_TEST_SERVER_TOKEN, $tk->TEST_TIMEOUT);
 
         // remove all suppressions on the default stream
-        $sups = $client->getSuppressions();
-        foreach ($sups->getSuppressions() as $sup) {
-            $suppressionChanges = [new SuppressionChangeRequest($sup->getEmailAddress())];
-            $messageStream = 'outbound';
-            $client->deleteSuppressions($suppressionChanges, $messageStream);
+        try {
+            $sups = $client->getSuppressions();
+            $suppressions = $sups->getSuppressions();
+            if (!empty($suppressions)) {
+                foreach ($suppressions as $sup) {
+                    $suppressionChanges = [new SuppressionChangeRequest($sup->getEmailAddress())];
+                    $messageStream = 'outbound';
+                    $client->deleteSuppressions($suppressionChanges, $messageStream);
+                }
+            }
+        } catch (PostmarkException $e) {
+            // Ignore errors during cleanup
         }
     }