diff --git a/src/Client.php b/src/Client.php
index 927982da..c6a718dd 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -17,8 +17,7 @@
 use Bugsnag\Middleware\SessionData;
 use Bugsnag\Request\BasicResolver;
 use Bugsnag\Request\ResolverInterface;
-use Composer\CaBundle\CaBundle;
-use GuzzleHttp\Client as Guzzle;
+use Bugsnag\Utils;
 use GuzzleHttp\ClientInterface;
 use ReflectionClass;
 use ReflectionException;
@@ -30,7 +29,7 @@ class Client
      *
      * @var string
      */
-    const ENDPOINT = 'https://notify.bugsnag.com';
+    const ENDPOINT = Configuration::DEFAULT_NOTIFY_ENDPOINT;
 
     /**
      * The config instance.
@@ -88,10 +87,13 @@ class Client
     public static function make($apiKey = null, $endpoint = null, $defaults = true)
     {
         $config = new Configuration($apiKey ?: getenv('BUGSNAG_API_KEY'));
-        $guzzle = static::makeGuzzle($endpoint ?: getenv('BUGSNAG_ENDPOINT'));
 
-        $client = new static($config, null, $guzzle);
+        if ($endpoint = $endpoint ?: getenv('BUGSNAG_ENDPOINT')) {
+            $sessionEndpoint = getenv('BUGSNAG_SESSION_ENDPOINT');
+            $config->setEndpoints($endpoint, $sessionEndpoint);
+        }
 
+        $client = new static($config, null, null);
         if ($defaults) {
             $client->registerDefaultCallbacks();
         }
@@ -111,10 +113,20 @@ public static function make($apiKey = null, $endpoint = null, $defaults = true)
     public function __construct(Configuration $config, ResolverInterface $resolver = null, ClientInterface $guzzle = null)
     {
         $this->config = $config;
+        if ($guzzle) {
+            $this->config->setGuzzleClient($guzzle);
+            if (version_compare(ClientInterface::VERSION, '6') === 1) {
+                $endpoint = $guzzle->getConfig('base_uri');
+            } else {
+                $endpoint = $guzzle->getBaseUrl();
+            }
+            $this->config->setEndpoints((string) $endpoint, null);
+        }
+
         $this->resolver = $resolver ?: new BasicResolver();
         $this->recorder = new Recorder();
         $this->pipeline = new Pipeline();
-        $this->http = new HttpClient($config, $guzzle ?: static::makeGuzzle());
+        $this->http = new HttpClient($config);
         $this->sessionTracker = new SessionTracker($config);
 
         $this->registerMiddleware(new NotificationSkipper($config));
@@ -135,28 +147,8 @@ public function __construct(Configuration $config, ResolverInterface $resolver =
     public static function makeGuzzle($base = null, array $options = [])
     {
         $key = version_compare(ClientInterface::VERSION, '6') === 1 ? 'base_uri' : 'base_url';
-
         $options[$key] = $base ?: static::ENDPOINT;
-
-        if ($path = static::getCaBundlePath()) {
-            $options['verify'] = $path;
-        }
-
-        return new Guzzle($options);
-    }
-
-    /**
-     * Get the ca bundle path if one exists.
-     *
-     * @return string|false
-     */
-    protected static function getCaBundlePath()
-    {
-        if (!class_exists(CaBundle::class)) {
-            return false;
-        }
-
-        return realpath(CaBundle::getSystemCaRootBundlePath());
+        return Utils::makeGuzzle($options);
     }
 
     /**
@@ -784,6 +776,41 @@ public function setAutoCaptureSessions($track)
         return $this;
     }
 
+    /**
+     * Sets the notify and session endpoints
+     *
+     * @param string $notifyEndpoint the notify endpoint
+     * @param string $sessionEndpoint the session endpoint
+     *
+     * @return $this
+     */
+    public function setEndpoints($notifyEndpoint, $sessionEndpoint)
+    {
+        $this->config->setEndpoints($notifyEndpoint, $sessionEndpoint);
+
+        return $this;
+    }
+
+    /**
+     * Gets the notify endpoint
+     *
+     * @return string
+     */
+    public function getNotifyEndpoint()
+    {
+        return $this->config->getNotifyEndpoint();
+    }
+
+    /**
+     * Gets the session endpoint
+     *
+     * @return string
+     */
+    public function getSessionEndpoint()
+    {
+        return $this->config->getSessionEndpoint();
+    }
+
     /**
      * Set session delivery endpoint.
      *
@@ -808,6 +835,41 @@ public function getSessionClient()
         return $this->config->getSessionClient();
     }
 
+    /**
+     * Gets the current guzzle client.
+     *
+     * @return GuzzleHttp\ClientInterface
+     */
+    public function getGuzzleClient()
+    {
+        return $this->config->getGuzzleClient();
+    }
+
+    /**
+     * Sets the guzzle client
+     *
+     * Delivery URLs should be set using the "setEndpoints" method
+     *
+     * @param GuzzleHttp\ClientInterface $guzzleClient the new guzzle client
+     *
+     * @return $this
+     */
+    public function setGuzzleClient($guzzleClient)
+    {
+        $this->config->setGuzzleClient($guzzleClient);
+        return $this;
+    }
+
+    /**
+     * Whether any sessions are enabled.
+     *
+     * @return bool
+     */
+    public function sessionsEnabled()
+    {
+        return $this->config->sessionsEnabled();
+    }
+
     /**
      * Whether should be auto-capturing sessions.
      *
diff --git a/src/Configuration.php b/src/Configuration.php
index 51201fa8..a7581e5c 100644
--- a/src/Configuration.php
+++ b/src/Configuration.php
@@ -3,22 +3,30 @@
 namespace Bugsnag;
 
 use InvalidArgumentException;
+use Bugsnag\Utils;
 
 class Configuration
 {
     /**
-     * The default endpoint.
+     * The default notification endpoint.
      *
      * @var string
      */
-    const SESSION_ENDPOINT = 'https://sessions.bugsnag.com';
+    const DEFAULT_NOTIFY_ENDPOINT = 'https://notify.bugsnag.com';
+
+    /**
+     * The default session endpoint.
+     *
+     * @var string
+     */
+    const DEFAULT_SESSION_ENDPOINT = 'https://sessions.bugsnag.com';
 
     /**
      * The default build endpoint.
      *
      * @var string
      */
-    const BUILD_ENDPOINT = 'https://build.bugsnag.com';
+    const DEFAULT_BUILD_ENDPOINT = 'https://build.bugsnag.com';
 
     /**
      * The Bugsnag API Key.
@@ -116,25 +124,39 @@ class Configuration
     protected $errorReportingLevel;
 
     /**
-     * Whether to track sessions.
+     * Whether to track sessions automatically.
+     *
+     * @var bool
+     */
+    protected $autoCaptureSessions = true;
+
+    /**
+     * Whether to allow any sessions to be tracked.
      *
      * @var bool
      */
-    protected $autoCaptureSessions = false;
+    protected $enableSessions = true;
 
     /**
-     * A client to use to send sessions.
+     * The client for making http requests
      *
-     * @var \Guzzle\ClientInterface
+     * @var GuzzleHttp\ClientInterface|null
      */
-    protected $sessionClient;
+    protected $guzzleClient = null;
+
+    /**
+     * The endpoint to deliver notifications to.
+     *
+     * @var string
+     */
+    protected $notifyEndpoint = self::DEFAULT_NOTIFY_ENDPOINT;
 
     /**
      * The endpoint to deliver sessions to.
      *
      * @var string
      */
-    protected $sessionEndpoint = self::SESSION_ENDPOINT;
+    protected $sessionEndpoint = self::DEFAULT_SESSION_ENDPOINT;
 
     /**
      * The endpoint to deliver build notifications to.
@@ -578,6 +600,75 @@ public function setAutoCaptureSessions($track)
         return $this;
     }
 
+    /**
+     * Whether any sessions are enabled.
+     *
+     * @return bool
+     */
+    public function sessionsEnabled()
+    {
+        if ($this->enableSessions) {
+            $notifyEndpointSet = $this->notifyEndpoint !== static::DEFAULT_NOTIFY_ENDPOINT;
+            $sessionEndpointSet = $this->sessionEndpoint !== static::DEFAULT_SESSION_ENDPOINT;
+            if ($notifyEndpointSet && !$sessionEndpointSet) {
+                syslog(LOG_WARNING, 'The session endpoint has not been set, all further session capturing will be disabled');
+                $this->enableSessions = false;
+            } elseif (!$notifyEndpointSet && $sessionEndpointSet) {
+                throw new InvalidArgumentException('The session endpoint cannot be modified without the notify endpoint');
+            }
+        }
+        return $this->enableSessions;
+    }
+
+    /**
+     * Whether should be auto-capturing sessions.
+     *
+     * @return bool
+     */
+    public function shouldCaptureSessions()
+    {
+        return $this->autoCaptureSessions && $this->sessionsEnabled();
+    }
+
+    /**
+     * Sets the notify and session endpoints
+     *
+     * @param string $notifyEndpoint the notify endpoint
+     * @param string $sessionEndpoint the session endpoint
+     *
+     * @return $this
+     */
+    public function setEndpoints($notifyEndpoint, $sessionEndpoint)
+    {
+        if ($notifyEndpoint) {
+            $this->notifyEndpoint = $notifyEndpoint;
+        }
+        if ($sessionEndpoint) {
+            $this->sessionEndpoint = $sessionEndpoint;
+        }
+        return $this;
+    }
+
+    /**
+     * Gets the notify endpoint
+     *
+     * @return string
+     */
+    public function getNotifyEndpoint()
+    {
+        return $this->notifyEndpoint;
+    }
+
+    /**
+     * Gets the session endpoint
+     *
+     * @return string
+     */
+    public function getSessionEndpoint()
+    {
+        return $this->sessionEndpoint;
+    }
+
     /**
      * Set session delivery endpoint.
      *
@@ -587,9 +678,7 @@ public function setAutoCaptureSessions($track)
      */
     public function setSessionEndpoint($endpoint)
     {
-        $this->sessionEndpoint = $endpoint;
-
-        $this->sessionClient = Client::makeGuzzle($this->sessionEndpoint);
+        $this->setEndpoints(null, $endpoint);
 
         return $this;
     }
@@ -601,21 +690,35 @@ public function setSessionEndpoint($endpoint)
      */
     public function getSessionClient()
     {
-        if (is_null($this->sessionClient)) {
-            $this->sessionClient = Client::makeGuzzle($this->sessionEndpoint);
-        }
+        return $this->getGuzzleClient();
+    }
 
-        return $this->sessionClient;
+    /**
+     * Sets the guzzle client
+     *
+     * Delivery URLs should be set using the "setEndpoints" method
+     *
+     * @param GuzzleHttp\ClientInterface $guzzleClient the new guzzle client
+     *
+     * @return $this
+     */
+    public function setGuzzleClient($guzzleClient)
+    {
+        $this->guzzleClient = $guzzleClient;
+        return $this;
     }
 
     /**
-     * Whether should be auto-capturing sessions.
+     * Gets the current guzzle client, making one if necessary
      *
-     * @return bool
+     * @return GuzzleHttp\ClientInterface
      */
-    public function shouldCaptureSessions()
+    public function getGuzzleClient()
     {
-        return $this->autoCaptureSessions;
+        if (!$this->guzzleClient) {
+            $this->guzzleClient = Utils::makeGuzzle();
+        }
+        return $this->guzzleClient;
     }
 
     /**
@@ -643,6 +746,6 @@ public function getBuildEndpoint()
             return $this->buildEndpoint;
         }
 
-        return self::BUILD_ENDPOINT;
+        return self::DEFAULT_BUILD_ENDPOINT;
     }
 }
diff --git a/src/HttpClient.php b/src/HttpClient.php
index 37a6419c..76f981a4 100644
--- a/src/HttpClient.php
+++ b/src/HttpClient.php
@@ -15,13 +15,6 @@ class HttpClient
      */
     protected $config;
 
-    /**
-     * The guzzle client instance.
-     *
-     * @var \GuzzleHttp\ClientInterface
-     */
-    protected $guzzle;
-
     /**
      * The queue of reports to send.
      *
@@ -47,14 +40,12 @@ class HttpClient
      * Create a new http client instance.
      *
      * @param \Bugsnag\Configuration      $config the configuration instance
-     * @param \GuzzleHttp\ClientInterface $guzzle the guzzle client instance
      *
      * @return void
      */
-    public function __construct(Configuration $config, ClientInterface $guzzle)
+    public function __construct(Configuration $config)
     {
         $this->config = $config;
-        $this->guzzle = $guzzle;
     }
 
     /**
@@ -149,7 +140,9 @@ public function sendBuildReport(array $buildInfo)
 
         $endpoint = $this->config->getBuildEndpoint();
 
-        $this->guzzle->post($endpoint, ['json' => $data]);
+        $guzzleClient = $this->config->getGuzzleClient();
+
+        $guzzleClient->post($endpoint, ['json' => $data]);
     }
 
     /**
@@ -163,7 +156,7 @@ public function send()
             return;
         }
 
-        $this->postJson('', $this->build());
+        $this->postJson($this->config->getNotifyEndpoint(), $this->build());
 
         $this->queue = [];
     }
@@ -236,8 +229,9 @@ protected function postJSON($url, $data)
         }
 
         // Send via guzzle and log any failures
+        $guzzleClient = $this->config->getGuzzleClient();
         try {
-            $this->guzzle->post($url, [
+            $guzzleClient->post($url, [
                 'json' => $normalized,
                 'headers' => $this->getHeaders(),
             ]);
diff --git a/src/SessionTracker.php b/src/SessionTracker.php
index 8e3f1238..53617acf 100644
--- a/src/SessionTracker.php
+++ b/src/SessionTracker.php
@@ -105,13 +105,11 @@ public function __construct(Configuration $config)
         $this->lastSent = 0;
     }
 
-    public function setConfig(Configuration $config)
-    {
-        $this->config = $config;
-    }
-
     public function startSession()
     {
+        if (!$this->config->sessionsEnabled()) {
+            return;
+        }
         $currentTime = strftime('%Y-%m-%dT%H:%M:00');
         $session = [
             'id' => uniqid('', true),
@@ -285,7 +283,7 @@ protected function deliverSessions()
         if (count($sessions) == 0) {
             return;
         }
-        $http = $this->config->getSessionClient();
+        $guzzle = $this->config->getGuzzleClient();
         $payload = $this->constructPayload($sessions);
         $headers = [
             'Bugsnag-Api-Key' => $this->config->getApiKey(),
@@ -295,7 +293,7 @@ protected function deliverSessions()
         $this->setLastSent();
 
         try {
-            $http->post('', [
+            $guzzle->post($this->config->getSessionEndpoint(), [
                 'json' => $payload,
                 'headers' => $headers,
             ]);
diff --git a/src/Utils.php b/src/Utils.php
index 5529061e..88be7296 100644
--- a/src/Utils.php
+++ b/src/Utils.php
@@ -2,6 +2,9 @@
 
 namespace Bugsnag;
 
+use Composer\CaBundle\CaBundle;
+use GuzzleHttp\Client as Guzzle;
+
 class Utils
 {
     /**
@@ -40,4 +43,34 @@ public static function getBuilderName()
 
         return $builderName;
     }
+
+    /**
+     * Make a new guzzle client instance.
+     *
+     * @param array       $options
+     *
+     * @return \GuzzleHttp\ClientInterface
+     */
+    public static function makeGuzzle(array $options = [])
+    {
+        if ($path = static::getCaBundlePath()) {
+            $options['verify'] = $path;
+        }
+
+        return new Guzzle($options);
+    }
+
+    /**
+     * Get the ca bundle path if one exists.
+     *
+     * @return string|false
+     */
+    protected static function getCaBundlePath()
+    {
+        if (!class_exists(CaBundle::class)) {
+            return false;
+        }
+
+        return realpath(CaBundle::getSystemCaRootBundlePath());
+    }
 }
diff --git a/tests/ClientTest.php b/tests/ClientTest.php
index 20d396c4..e9eda21e 100644
--- a/tests/ClientTest.php
+++ b/tests/ClientTest.php
@@ -30,7 +30,7 @@ protected function setUp()
 
         $this->client = $this->getMockBuilder(Client::class)
                              ->setMethods(['notify'])
-                             ->setConstructorArgs([$this->config = new Configuration('example-api-key'), null, $this->guzzle])
+                             ->setConstructorArgs([$this->config = new Configuration('example-api-key'), null])
                              ->getMock();
     }
 
@@ -43,13 +43,13 @@ public function testManualErrorNotification()
 
     public function testManualErrorNotificationWithSeverity()
     {
-        $client = new Client($this->config, null, $this->guzzle);
+        $client = new Client($this->config, null);
         $prop = (new ReflectionClass($client))->getProperty('http');
         $prop->setAccessible(true);
 
         $http = $this->getMockBuilder(HttpClient::class)
                      ->setMethods(['queue'])
-                     ->setConstructorArgs([$this->config, $this->guzzle])
+                     ->setConstructorArgs([$this->config])
                      ->getMock();
         $prop->setValue($client, $http);
 
@@ -80,26 +80,12 @@ public function testManualExceptionNotificationWithSeverity()
         });
     }
 
-    protected function getGuzzle(Client $client)
-    {
-        $prop = (new ReflectionClass($client))->getProperty('http');
-        $prop->setAccessible(true);
-
-        $http = $prop->getValue($client);
-
-        $prop = (new ReflectionClass($http))->getProperty('guzzle');
-        $prop->setAccessible(true);
-
-        return $prop->getValue($http);
-    }
-
     public function testDefaultSetup()
     {
-        if (version_compare(ClientInterface::VERSION, '6') === 1) {
-            $this->assertEquals(new Uri('https://notify.bugsnag.com'), $this->getGuzzle(Client::make('123'))->getConfig('base_uri'));
-        } else {
-            $this->assertSame('https://notify.bugsnag.com', $this->getGuzzle(Client::make('123'))->getBaseUrl());
-        }
+        $client = Client::make('123');
+
+        $this->assertEquals(Configuration::DEFAULT_NOTIFY_ENDPOINT, $client->getNotifyEndpoint());
+        $this->assertEquals(Configuration::DEFAULT_SESSION_ENDPOINT, $client->getSessionEndpoint());
     }
 
     public function testCanMake()
@@ -107,33 +93,51 @@ public function testCanMake()
         $client = Client::make('123', 'https://example.com');
 
         $this->assertInstanceOf(Client::class, $client);
-
-        if (version_compare(ClientInterface::VERSION, '6') === 1) {
-            $this->assertEquals(new Uri('https://example.com'), $this->getGuzzle($client)->getConfig('base_uri'));
-        } else {
-            $this->assertSame('https://example.com', $this->getGuzzle($client)->getBaseUrl());
-        }
+        $this->assertEquals('https://example.com', $client->getNotifyEndpoint());
     }
 
     public function testCanMakeFromEnv()
     {
+        $endpoint = 'endpoint';
         $env = $this->getFunctionMock('Bugsnag', 'getenv');
-        $env->expects($this->exactly(2))->will($this->returnValue('http://foo.com'));
+        $env->expects($this->exactly(3))->will($this->returnValue($endpoint));
 
         $client = Client::make();
 
         $this->assertInstanceOf(Client::class, $client);
+        $this->assertSame($endpoint, $client->getNotifyEndpoint());
+        $this->assertSame($endpoint, $client->getSessionEndpoint());
+    }
+
+    public function testCanConstructWithGuzzle()
+    {
+        $guzzle = Client::makeGuzzle("https://example.com");
 
-        if (version_compare(ClientInterface::VERSION, '6') === 1) {
-            $this->assertEquals(new Uri('http://foo.com'), $this->getGuzzle($client)->getConfig('base_uri'));
-        } else {
-            $this->assertSame('http://foo.com', $this->getGuzzle($client)->getBaseUrl());
-        }
+        $this->assertSame(Guzzle::class, get_class($guzzle));
+
+        $client = new Client(new Configuration('123'), null, $guzzle);
+
+        $this->assertSame($guzzle, $client->getGuzzleClient());
+        $this->assertEquals('https://example.com', $client->getNotifyEndpoint());
+    }
+
+    public function testCanSetEndpointsIndependently()
+    {
+        $guzzle = Client::makeGuzzle("https://example.com");
+
+        $client = new Client(new Configuration('123'), null, $guzzle);
+
+        $client->setSessionEndpoint("https://sessions-example.com");
+
+        $this->assertEquals('https://example.com', $client->getNotifyEndpoint());
+        $this->assertEquals('https://sessions-example.com', $client->getSessionEndpoint());
+        $this->assertTrue($client->sessionsEnabled());
     }
 
     public function testBeforeNotifySkipsError()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->setBatchSending(false);
 
@@ -150,8 +154,8 @@ public function testBeforeNotifySkipsError()
 
     public function testBeforeNotifyCanModifyReportFrames()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
-
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
         $this->client->setBatchSending(false);
 
         $this->client->notify($report = Report::fromNamedError($this->config, 'Magic', 'oh no'));
@@ -172,7 +176,8 @@ public function testBeforeNotifyCanModifyReportFrames()
 
     public function testDirectCallbackSkipsError()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->setBatchSending(false);
 
@@ -187,7 +192,8 @@ public function testDirectCallbackSkipsError()
 
     public function testMetaDataWorks()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->notify($report = Report::fromNamedError($this->config, 'Name'), function ($report) {
             $report->setMetaData(['foo' => 'baz']);
@@ -198,7 +204,8 @@ public function testMetaDataWorks()
 
     public function testCustomMiddlewareWorks()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->registerMiddleware(function ($report, callable $next) {
             $report->setMetaData(['middleware' => 'registered']);
@@ -212,7 +219,8 @@ public function testCustomMiddlewareWorks()
 
     public function testMiddlewareCanModifySeverity()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->registerMiddleware(function ($report, callable $next) {
             $report->setSeverity('info');
@@ -229,7 +237,8 @@ public function testMiddlewareCanModifySeverity()
 
     public function testMiddlewareCanModifyUnhandled()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->registerMiddleware(function ($report, callable $next) {
             $report->setUnhandled(true);
@@ -246,7 +255,8 @@ public function testMiddlewareCanModifyUnhandled()
 
     public function testMiddlewareCanModifySeverityReason()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->registerMiddleware(function ($report, callable $next) {
             $report->setSeverityReason([
@@ -267,7 +277,8 @@ public function testMiddlewareCanModifySeverityReason()
 
     public function testNotOverriddenByCallbacks()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->registerMiddleware(function ($report, callable $next) {
             $report->setUnhandled(true);
@@ -315,7 +326,8 @@ public function testBreadcrumbsWorks()
 
     public function testBreadcrumbsFallback()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->leaveBreadcrumb('Foo Bar Baz', 'bla');
 
@@ -334,7 +346,8 @@ public function testBreadcrumbsFallback()
 
     public function testBreadcrumbsNoName()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         // notify with an empty report name
         $this->client->notify(Report::fromNamedError($this->config, ''));
@@ -355,7 +368,8 @@ public function testBreadcrumbsNoName()
 
     public function testBreadcrumbsGetShortNameClass()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->config->setGuzzleClient($this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
 
         $this->client->leaveBreadcrumb(Client::class, 'state');
 
@@ -374,7 +388,8 @@ public function testBreadcrumbsGetShortNameClass()
 
     public function testBreadcrumbsLong()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->leaveBreadcrumb('This error name is far too long to be allowed through.', 'user', ['foo' => 'bar']);
 
@@ -393,7 +408,8 @@ public function testBreadcrumbsLong()
 
     public function testBreadcrumbsLarge()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->leaveBreadcrumb('Test', 'user', ['foo' => str_repeat('A', 5000)]);
 
@@ -412,8 +428,9 @@ public function testBreadcrumbsLarge()
 
     public function testBreadcrumbsAgain()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
 
+        $this->config->setGuzzleClient($this->guzzle);
         $this->client->leaveBreadcrumb('Test', 'user', ['foo' => 'bar']);
 
         $this->client->notify($report = Report::fromNamedError($this->config, 'Name'));
@@ -459,7 +476,8 @@ public function testNoEnvironmentByDefault()
     {
         $_ENV['SOMETHING'] = 'blah';
 
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->registerDefaultCallbacks();
 
@@ -472,9 +490,11 @@ public function testBatchingDoesNotFlush()
     {
         $this->client = $this->getMockBuilder(Client::class)
                              ->setMethods(['flush'])
-                             ->setConstructorArgs([$this->config, null, $this->guzzle])
+                             ->setConstructorArgs([$this->config, null])
                              ->getMock();
 
+        $this->config->setGuzzleClient($this->guzzle);
+
         $this->client->expects($this->never())->method('flush');
 
         $this->client->notify($report = Report::fromNamedError($this->config, 'Name'));
@@ -484,9 +504,11 @@ public function testFlushesWhenNotBatching()
     {
         $this->client = $this->getMockBuilder(Client::class)
                              ->setMethods(['flush'])
-                             ->setConstructorArgs([$this->config, null, $this->guzzle])
+                             ->setConstructorArgs([$this->config, null])
                              ->getMock();
 
+        $this->config->setGuzzleClient($this->guzzle);
+
         $this->client->expects($this->once())->method('flush');
 
         $this->client->setBatchSending(false);
@@ -496,7 +518,8 @@ public function testFlushesWhenNotBatching()
 
     public function testCanManuallyFlush()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->setBatchSending(false);
 
@@ -512,82 +535,61 @@ public function testCanManuallyFlush()
     public function testDeployWorksOutOfTheBox()
     {
         $this->guzzle->expects($this->once())->method('post')->with($this->equalTo('https://build.bugsnag.com'), $this->equalTo(['json' => ['releaseStage' => 'production', 'apiKey' => 'example-api-key', 'buildTool' => 'bugsnag-php', 'builderName' => exec('whoami'), 'appVersion' => '1.3.1']]));
-
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+         $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
         $this->config->setAppVersion('1.3.1');
-
-        $this->client->deploy();
+         $this->client->deploy();
     }
-
-    public function testDeployWorksWithReleaseStage()
+     public function testDeployWorksWithReleaseStage()
     {
         $this->guzzle->expects($this->once())->method('post')->with($this->equalTo('https://build.bugsnag.com'), $this->equalTo(['json' => ['releaseStage' => 'staging', 'apiKey' => 'example-api-key', 'buildTool' => 'bugsnag-php', 'builderName' => exec('whoami'), 'appVersion' => '1.3.1']]));
-
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+         $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
         $this->config->setAppVersion('1.3.1');
-
-        $this->config->setReleaseStage('staging');
-
-        $this->client->deploy();
+         $this->config->setReleaseStage('staging');
+         $this->client->deploy();
     }
-
-    public function testDeployWorksWithAppVersion()
+     public function testDeployWorksWithAppVersion()
     {
         $this->guzzle->expects($this->once())->method('post')->with($this->equalTo('https://build.bugsnag.com'), $this->equalTo(['json' => ['releaseStage' => 'production', 'appVersion' => '1.1.0', 'apiKey' => 'example-api-key', 'buildTool' => 'bugsnag-php', 'builderName' => exec('whoami'), 'appVersion' => '1.3.1']]));
-
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+         $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
         $this->config->setAppVersion('1.3.1');
-
-        $this->client->deploy();
+         $this->client->deploy();
     }
-
-    public function testDeployWorksWithRepository()
+     public function testDeployWorksWithRepository()
     {
         $this->guzzle->expects($this->once())->method('post')->with($this->equalTo('https://build.bugsnag.com'), $this->equalTo(['json' => ['sourceControl' => ['repository' => 'foo'], 'releaseStage' => 'production', 'apiKey' => 'example-api-key', 'buildTool' => 'bugsnag-php', 'builderName' => exec('whoami'), 'appVersion' => '1.3.1']]));
-
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+         $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
         $this->config->setAppVersion('1.3.1');
-
-        $this->client->deploy('foo');
+         $this->client->deploy('foo');
     }
-
-    public function testDeployWorksWithBranch()
+     public function testDeployWorksWithBranch()
     {
         $this->guzzle->expects($this->once())->method('post')->with($this->equalTo('https://build.bugsnag.com'), $this->equalTo(['json' => ['releaseStage' => 'production', 'apiKey' => 'example-api-key', 'buildTool' => 'bugsnag-php', 'builderName' => exec('whoami'), 'appVersion' => '1.3.1']]));
-
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+         $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
         $this->config->setAppVersion('1.3.1');
-
-        $this->client->deploy(null, 'master');
+         $this->client->deploy(null, 'master');
     }
-
-    public function testDeployWorksWithRevision()
+     public function testDeployWorksWithRevision()
     {
         $this->guzzle->expects($this->once())->method('post')->with($this->equalTo('https://build.bugsnag.com'), $this->equalTo(['json' => ['sourceControl' => ['revision' => 'bar'], 'releaseStage' => 'production', 'apiKey' => 'example-api-key', 'buildTool' => 'bugsnag-php', 'builderName' => exec('whoami'), 'appVersion' => '1.3.1']]));
-
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+         $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
         $this->config->setAppVersion('1.3.1');
-
-        $this->client->deploy(null, null, 'bar');
+         $this->client->deploy(null, null, 'bar');
     }
-
-    public function testDeployWorksWithEverything()
+     public function testDeployWorksWithEverything()
     {
         $this->guzzle->expects($this->once())->method('post')->with($this->equalTo('https://build.bugsnag.com'), $this->equalTo(['json' => ['sourceControl' => ['repository' => 'baz', 'revision' => 'foo'], 'releaseStage' => 'development', 'appVersion' => '1.3.1', 'apiKey' => 'example-api-key', 'buildTool' => 'bugsnag-php', 'builderName' => exec('whoami'), 'appVersion' => '1.3.1']]));
-
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
-
-        $this->config->setReleaseStage('development');
+         $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+         $this->config->setReleaseStage('development');
         $this->config->setAppVersion('1.3.1');
-
-        $this->client->deploy('baz', 'develop', 'foo');
+         $this->client->deploy('baz', 'develop', 'foo');
     }
 
     public function testBuildWorksOutOfTheBox()
     {
         $this->guzzle->expects($this->once())->method('post')->with($this->equalTo('https://build.bugsnag.com'), $this->equalTo(['json' => ['releaseStage' => 'production', 'apiKey' => 'example-api-key', 'buildTool' => 'bugsnag-php', 'builderName' => exec('whoami'), 'appVersion' => '1.3.1']]));
 
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
         $this->config->setAppVersion('1.3.1');
 
         $this->client->build();
@@ -597,7 +599,8 @@ public function testBuildWorksWithReleaseStage()
     {
         $this->guzzle->expects($this->once())->method('post')->with($this->equalTo('https://build.bugsnag.com'), $this->equalTo(['json' => ['releaseStage' => 'staging', 'apiKey' => 'example-api-key', 'buildTool' => 'bugsnag-php', 'builderName' => exec('whoami'), 'appVersion' => '1.3.1']]));
 
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->config->setAppVersion('1.3.1');
         $this->config->setReleaseStage('staging');
@@ -609,7 +612,8 @@ public function testBuildWorksWithRepository()
     {
         $this->guzzle->expects($this->once())->method('post')->with($this->equalTo('https://build.bugsnag.com'), $this->equalTo(['json' => ['sourceControl' => ['repository' => 'foo'], 'releaseStage' => 'production', 'apiKey' => 'example-api-key', 'buildTool' => 'bugsnag-php', 'builderName' => exec('whoami'), 'appVersion' => '1.3.1']]));
 
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
         $this->config->setAppVersion('1.3.1');
 
         $this->client->build('foo');
@@ -619,8 +623,9 @@ public function testBuildWorksWithProvider()
     {
         $this->guzzle->expects($this->once())->method('post')->with($this->equalTo('https://build.bugsnag.com'), $this->equalTo(['json' => ['sourceControl' => ['provider' => 'github'], 'releaseStage' => 'production', 'apiKey' => 'example-api-key', 'buildTool' => 'bugsnag-php', 'builderName' => exec('whoami'), 'appVersion' => '1.3.1']]));
 
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
         $this->config->setAppVersion('1.3.1');
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->build(null, null, 'github');
     }
@@ -629,8 +634,9 @@ public function testBuildWorksWithRevision()
     {
         $this->guzzle->expects($this->once())->method('post')->with($this->equalTo('https://build.bugsnag.com'), $this->equalTo(['json' => ['sourceControl' => ['revision' => 'bar'], 'releaseStage' => 'production', 'apiKey' => 'example-api-key', 'buildTool' => 'bugsnag-php', 'builderName' => exec('whoami'), 'appVersion' => '1.3.1']]));
 
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
         $this->config->setAppVersion('1.3.1');
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->build(null, 'bar');
     }
@@ -639,8 +645,9 @@ public function testBuildWorksWithBuilderName()
     {
         $this->guzzle->expects($this->once())->method('post')->with($this->equalTo('https://build.bugsnag.com'), $this->equalTo(['json' => ['builderName' => 'me', 'releaseStage' => 'production', 'apiKey' => 'example-api-key', 'buildTool' => 'bugsnag-php', 'appVersion' => '1.3.1']]));
 
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
         $this->config->setAppVersion('1.3.1');
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->build(null, null, null, 'me');
     }
@@ -649,8 +656,9 @@ public function testBuildWorksWithBuildTool()
     {
         $this->guzzle->expects($this->once())->method('post')->with($this->equalTo('https://build.bugsnag.com'), $this->equalTo(['json' => ['releaseStage' => 'production', 'apiKey' => 'example-api-key', 'buildTool' => 'bugsnag-php', 'builderName' => exec('whoami'), 'appVersion' => '1.3.1']]));
 
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
         $this->config->setAppVersion('1.3.1');
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->build(null, null, null, null);
     }
@@ -659,7 +667,8 @@ public function testBuildWorksWithEverything()
     {
         $this->guzzle->expects($this->once())->method('post')->with($this->equalTo('https://build.bugsnag.com'), $this->equalTo(['json' => ['builderName' => 'me', 'sourceControl' => ['repository' => 'baz', 'revision' => 'foo', 'provider' => 'github'], 'releaseStage' => 'development', 'appVersion' => '1.3.1', 'apiKey' => 'example-api-key', 'buildTool' => 'bugsnag-php']]));
 
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->config->setReleaseStage('development');
         $this->config->setAppVersion('1.3.1');
@@ -669,7 +678,8 @@ public function testBuildWorksWithEverything()
 
     public function testBuildFailsWithoutAPIKey()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         // Setup error_log mocking
         $log = $this->getFunctionMock('Bugsnag', 'error_log');
@@ -680,7 +690,8 @@ public function testBuildFailsWithoutAPIKey()
 
     public function testSeverityReasonUnmodified()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $this->client->notify($report = Report::fromNamedError($this->config, 'Name'));
 
@@ -691,7 +702,8 @@ public function testSeverityReasonUnmodified()
 
     public function testSeverityModifiedByCallback()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $report = Report::fromNamedError($this->config, 'Name');
 
@@ -707,7 +719,8 @@ public function testSeverityModifiedByCallback()
 
     public function testSeverityReasonNotModifiedByCallback()
     {
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
 
         $report = Report::fromNamedError($this->config, 'Name', null, false, ['type' => 'handledError']);
 
@@ -727,7 +740,8 @@ public function testUrlModifiableByCallback()
         $_SERVER['HTTP_HOST'] = 'test.com';
         $_SERVER['REQUEST_URI'] = '/blah/blah.php?user=anon&password=hunter2';
 
-        $this->client = new Client($this->config = new Configuration('example-api-key'), null, $this->guzzle);
+        $this->client = new Client($this->config = new Configuration('example-api-key'), null);
+        $this->config->setGuzzleClient($this->guzzle);
         $this->client->registerDefaultCallbacks();
 
         $report = Report::fromNamedError($this->config, 'Name');
@@ -836,15 +850,8 @@ public function testSessionClient()
         $this->assertSame($client, $client->setSessionEndpoint('https://example'));
         $sessionClient = $client->getSessionClient();
         $this->assertSame(Guzzle::class, get_class($sessionClient));
-
-        if (substr(ClientInterface::VERSION, 0, 1) == '5') {
-            $clientUri = $sessionClient->getBaseUrl();
-        } else {
-            $baseUri = $sessionClient->getConfig('base_uri');
-            $clientUri = $baseUri->getScheme().'://'.$baseUri->getHost();
-        }
-
-        $this->assertSame('https://example', $clientUri);
+        $this->assertSame($client->getGuzzleClient(), $sessionClient);
+        $this->assertSame('https://example', $client->getSessionEndpoint());
     }
 
     public function testSetAutoCaptureSessions()
@@ -899,4 +906,39 @@ public function testNotifier()
         $this->assertSame($client, $client->setNotifier(['foo' => 'bar']));
         $this->assertSame(['foo' => 'bar'], $client->getNotifier());
     }
+
+    public function testSetEndpoints()
+    {
+        $client = Client::make('foo');
+        $this->assertSame(\Bugsnag\Configuration::DEFAULT_NOTIFY_ENDPOINT, $client->getNotifyEndpoint());
+        $this->assertSame(\Bugsnag\Configuration::DEFAULT_SESSION_ENDPOINT, $client->getSessionEndpoint());
+
+        $notify = "notify";
+        $session = "session";
+        $this->assertSame($client, $client->setEndpoints($notify, $session));
+
+        $this->assertSame($notify, $client->getNotifyEndpoint());
+        $this->assertSame($session, $client->getSessionEndpoint());
+    }
+
+    public function testSessionsEnabled()
+    {
+        $client = Client::make('foo');
+        $this->assertTrue($client->sessionsEnabled());
+
+        $client->setEndpoints("notify", null);
+
+        $this->assertFalse($client->sessionsEnabled());
+        $this->assertFalse($client->shouldCaptureSessions());
+    }
+
+    public function testSetGuzzleClient()
+    {
+        $client = Client::make('foo');
+        $this->assertInstanceOf(Guzzle::class, $client->getGuzzleClient());
+
+        $guzzle = new Guzzle();
+        $this->assertSame($client, $client->setGuzzleClient($guzzle));
+        $this->assertSame($guzzle, $client->getGuzzleClient());
+    }
 }
diff --git a/tests/ConfigurationTest.php b/tests/ConfigurationTest.php
index 90d9ce11..314cc718 100644
--- a/tests/ConfigurationTest.php
+++ b/tests/ConfigurationTest.php
@@ -5,10 +5,14 @@
 use Bugsnag\Configuration;
 use GuzzleHttp\Client as GuzzleClient;
 use GuzzleHttp\ClientInterface;
+use phpmock\phpunit\PHPMock;
 use PHPUnit_Framework_TestCase as TestCase;
 
 class ConfigurationTest extends TestCase
 {
+
+    use PHPMock;
+
     protected $config;
 
     protected function setUp()
@@ -227,54 +231,93 @@ public function testDeviceData()
 
     public function testSessionTrackingDefaults()
     {
-        $this->assertFalse($this->config->shouldCaptureSessions());
+        $this->assertTrue($this->config->shouldCaptureSessions());
+        $this->assertTrue($this->config->sessionsEnabled());
     }
 
-    public function testSessionTrackingSetTrue()
+    public function testSessionTrackingSetFalse()
     {
+        $this->assertTrue($this->config->shouldCaptureSessions());
+
+        $this->config->setAutoCaptureSessions(false);
+
         $this->assertFalse($this->config->shouldCaptureSessions());
+    }
 
-        $this->config->setAutoCaptureSessions(true);
+    public function testSessionTrackingSetEndpoint()
+    {
+        $testUrl = 'https://testurl.com';
+        $this->config->setSessionEndpoint($testUrl);
 
-        $this->assertTrue($this->config->shouldCaptureSessions());
+        $this->assertSame($testUrl, $this->config->getSessionEndpoint());
+    }
 
-        $client = $this->config->getSessionClient();
+    public function testEndpointDefaults()
+    {
+        $this->assertSame(\Bugsnag\Configuration::DEFAULT_NOTIFY_ENDPOINT, $this->config->getNotifyEndpoint());
+        $this->assertSame(\Bugsnag\Configuration::DEFAULT_SESSION_ENDPOINT, $this->config->getSessionEndpoint());
+        $this->assertSame(\Bugsnag\Configuration::DEFAULT_BUILD_ENDPOINT, $this->config->getBuildEndpoint());
+    }
 
-        $this->assertSame(GuzzleClient::class, get_class($client));
+    public function testSetEndpointsBothValid()
+    {
+        $notifyUrl = 'notify';
+        $sessionUrl = 'session';
 
-        if (substr(ClientInterface::VERSION, 0, 1) == '5') {
-            $clientUri = $client->getBaseUrl();
-        } else {
-            $baseUri = $client->getConfig('base_uri');
-            $clientUri = $baseUri->getScheme().'://'.$baseUri->getHost();
-        }
+        $this->config->setEndpoints($notifyUrl, $sessionUrl);
 
-        $this->assertSame(Configuration::SESSION_ENDPOINT, $clientUri);
+        $this->assertSame($notifyUrl, $this->config->getNotifyEndpoint());
+        $this->assertSame($sessionUrl, $this->config->getSessionEndpoint());
     }
 
-    public function testSessionTrackingSetEndpoint()
+    public function testSetEndpointsNoChange()
     {
-        $testUrl = 'https://testurl.com';
+        // If this throws or logs, something has gone wrong
+        $this->config->setEndpoints(null, null);
 
-        $this->assertFalse($this->config->shouldCaptureSessions());
+        $this->assertSame(\Bugsnag\Configuration::DEFAULT_NOTIFY_ENDPOINT, $this->config->getNotifyEndpoint());
+        $this->assertSame(\Bugsnag\Configuration::DEFAULT_SESSION_ENDPOINT, $this->config->getSessionEndpoint());
+    }
 
-        $this->config->setAutoCaptureSessions(true);
+    public function testSetEndpointsNotifyNotSession()
+    {
+        $notifyUrl = 'notify';
 
-        $this->assertTrue($this->config->shouldCaptureSessions());
+        $env = $this->getFunctionMock('Bugsnag', 'syslog');
+        $env->expects($this->once())->with(LOG_WARNING, 'The session endpoint has not been set, all further session capturing will be disabled');
 
-        $this->config->setSessionEndpoint($testUrl);
+        $this->config->setEndpoints($notifyUrl, null);
+
+        $this->assertSame($notifyUrl, $this->config->getNotifyEndpoint());
+        $this->assertSame(\Bugsnag\Configuration::DEFAULT_SESSION_ENDPOINT, $this->config->getSessionEndpoint());
+        $this->assertFalse($this->config->sessionsEnabled());
+        $this->assertFalse($this->config->shouldCaptureSessions());
+    }
+
+    /**
+     * @expectedException \InvalidArgumentException
+     * @expectedExceptionMessage The session endpoint cannot be modified without the notify endpoint
+     */
+    public function testSetEndpointsSessionNotNotify()
+    {
+        $sessionUrl = 'session';
 
-        $client = $this->config->getSessionClient();
+        $this->config->setEndpoints(null, $sessionUrl);
+        $this->config->sessionsEnabled();
+    }
 
-        $this->assertSame(GuzzleClient::class, get_class($client));
+    public function testSetGuzzleClient()
+    {
+        $guzzleClient = new GuzzleClient();
 
-        if (substr(ClientInterface::VERSION, 0, 1) == '5') {
-            $clientUri = $client->getBaseUrl();
-        } else {
-            $baseUri = $client->getConfig('base_uri');
-            $clientUri = $baseUri->getScheme().'://'.$baseUri->getHost();
-        }
+        $this->config->setGuzzleClient($guzzleClient);
+        $this->assertSame($guzzleClient, $this->config->getGuzzleClient());
+    }
 
-        $this->assertSame($testUrl, $clientUri);
+    public function testGetGuzzleClientCreation()
+    {
+        $guzzle = $this->config->getGuzzleClient();
+        $this->assertInstanceOf(GuzzleClient::class, $guzzle);
     }
+
 }
diff --git a/tests/HttpClientTest.php b/tests/HttpClientTest.php
index 7854ba0e..fb6174a0 100644
--- a/tests/HttpClientTest.php
+++ b/tests/HttpClientTest.php
@@ -20,13 +20,13 @@ class HttpClientTest extends TestCase
 
     protected function setUp()
     {
-        $this->config = new Configuration('6015a72ff14038114c3d12623dfb018f');
-
         $this->guzzle = $this->getMockBuilder(Client::class)
                              ->setMethods(['post'])
                              ->getMock();
+        $this->config = new Configuration('6015a72ff14038114c3d12623dfb018f');
+        $this->config->setGuzzleClient($this->guzzle);
 
-        $this->http = new HttpClient($this->config, $this->guzzle);
+        $this->http = new HttpClient($this->config);
     }
 
     public function testHttpClient()
@@ -41,7 +41,7 @@ public function testHttpClient()
         $this->assertCount(1, $invocations = $spy->getInvocations());
         $params = $invocations[0]->parameters;
         $this->assertCount(2, $params);
-        $this->assertSame('', $params[0]);
+        $this->assertSame(\Bugsnag\Configuration::DEFAULT_NOTIFY_ENDPOINT, $params[0]);
         $this->assertInternalType('array', $params[1]);
         $this->assertInternalType('array', $params[1]['json']['notifier']);
         $this->assertInternalType('array', $params[1]['json']['events']);
@@ -56,6 +56,25 @@ public function testHttpClient()
         $this->assertSame('4.0', $headers['Bugsnag-Payload-Version']);
     }
 
+    public function testHttpClientUsesConfigSettings()
+    {
+        $config = $this->getMockBuilder(Configuration::class)
+                       ->disableOriginalConstructor()
+                       ->setMethods(['getNotifyEndpoint', 'getGuzzleClient'])
+                       ->getMock();
+
+        // Expect Client to get the guzzleClient and endpoint from Config
+        $config->expects($this->once())->method('getGuzzleClient')->willReturn($this->guzzle);
+        $config->expects($this->once())->method('getNotifyEndpoint')->willReturn('foo');
+
+        // Expect post to be called
+        $this->guzzle->expects($this->any())->method('post');
+
+        $http = new HttpClient($config);
+        $http->queue(Report::fromNamedError($this->config, 'Name'));
+        $http->send();
+    }
+
     public function testHttpClientMultipleSend()
     {
         // Expect request to be called
@@ -85,7 +104,7 @@ public function testMassiveMetaDataHttpClient()
         $this->assertCount(1, $invocations = $spy->getInvocations());
         $params = $invocations[0]->parameters;
         $this->assertCount(2, $params);
-        $this->assertSame('', $params[0]);
+        $this->assertSame(\Bugsnag\Configuration::DEFAULT_NOTIFY_ENDPOINT, $params[0]);
         $this->assertInternalType('array', $params[1]);
         $this->assertInternalType('array', $params[1]['json']['notifier']);
         $this->assertInternalType('array', $params[1]['json']['events']);
@@ -133,7 +152,7 @@ public function testPartialHttpClient()
         $this->assertCount(1, $invocations = $spy->getInvocations());
         $params = $invocations[0]->parameters;
         $this->assertCount(2, $params);
-        $this->assertSame('', $params[0]);
+        $this->assertSame(\Bugsnag\Configuration::DEFAULT_NOTIFY_ENDPOINT, $params[0]);
         $this->assertInternalType('array', $params[1]);
         $this->assertInternalType('array', $params[1]['json']['notifier']);
         $this->assertInternalType('array', $params[1]['json']['events']);