diff --git a/mazerunner/src/main/java/com/bugsnag/android/TestHarnessHooks.kt b/mazerunner/src/main/java/com/bugsnag/android/TestHarnessHooks.kt
index fab29e34ed..6cba832f00 100644
--- a/mazerunner/src/main/java/com/bugsnag/android/TestHarnessHooks.kt
+++ b/mazerunner/src/main/java/com/bugsnag/android/TestHarnessHooks.kt
@@ -2,8 +2,6 @@ package com.bugsnag.android
 
 import android.content.Context
 import android.net.ConnectivityManager
-import com.bugsnag.android.Bugsnag.client
-import java.util.*
 
 /**
  * Accesses the session tracker and flushes all stored sessions
@@ -12,39 +10,61 @@ internal fun flushAllSessions() {
     Bugsnag.getClient().sessionTracker.flushStoredSessions()
 }
 
-internal fun flushErrorStoreAsync(client: Client, apiClient: ErrorReportApiClient) {
-    client.errorStore.flushAsync(apiClient)
+internal fun flushErrorStoreAsync(client: Client) {
+    client.errorStore.flushAsync()
 }
 
-internal fun flushErrorStoreOnLaunch(client: Client, apiClient: ErrorReportApiClient) {
-    client.errorStore.flushOnLaunch(apiClient)
+internal fun flushErrorStoreOnLaunch(client: Client) {
+    client.errorStore.flushOnLaunch()
 }
 
 /**
- * Creates an error API client with a 500ms delay, emulating poor network connectivity
+ * Creates a delivery API client with a 500ms delay, emulating poor network connectivity
  */
-internal fun createSlowErrorApiClient(context: Context): ErrorReportApiClient {
+internal fun createSlowDelivery(context: Context): Delivery {
     val cm = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager?
-    val defaultHttpClient = DefaultHttpClient(cm)
-
-    return ErrorReportApiClient({ url: String?,
-                                  report: Report?,
-                                  headers: MutableMap<String, String>? ->
-        Thread.sleep(500)
-        defaultHttpClient.postReport(url, report, headers)
-    })
+    val delivery = DefaultDelivery(cm)
+
+    return object : Delivery {
+        override fun deliver(payload: SessionTrackingPayload?, config: Configuration?) {
+            Thread.sleep(500)
+            delivery.deliver(payload, config)
+        }
+
+        override fun deliver(report: Report?, config: Configuration?) {
+            Thread.sleep(500)
+            delivery.deliver(report, config)
+        }
+    }
 }
 
-internal fun createDefaultErrorClient(context: Context): ErrorReportApiClient {
+internal fun createDefaultDelivery(context: Context): DefaultDelivery {
     val cm = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager?
-    return DefaultHttpClient(cm)
+    return DefaultDelivery(cm)
 }
 
-internal fun createDefaultSessionClient(context: Context): SessionTrackingApiClient {
-    val cm = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager?
-    return DefaultHttpClient(cm)
+internal fun createCustomHeaderDelivery(context: Context): Delivery {
+    return object : Delivery {
+        val delivery: DefaultDelivery = createDefaultDelivery(context)
+
+        override fun deliver(payload: SessionTrackingPayload?, config: Configuration?) {
+            deliver(config?.sessionEndpoint, payload, config?.sessionApiHeaders)
+        }
+
+        override fun deliver(report: Report?, config: Configuration?) {
+            deliver(config?.endpoint, report, config?.errorApiHeaders)
+        }
+
+        fun deliver(endpoint: String?,
+                    streamable: JsonStream.Streamable?,
+                    headers: MutableMap<String, String>?) {
+            headers!!["Custom-Client"] = "Hello World"
+            delivery.deliver(endpoint, streamable, headers)
+        }
+    }
 }
 
+
 internal fun writeErrorToStore(client: Client) {
     val error = Error.Builder(Configuration("api-key"), RuntimeException(), null).build()
     client.errorStore.write(error)
diff --git a/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/AsyncErrorConnectivityScenario.kt b/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/AsyncErrorConnectivityScenario.kt
index acaa178216..7ca0ff67b3 100644
--- a/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/AsyncErrorConnectivityScenario.kt
+++ b/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/AsyncErrorConnectivityScenario.kt
@@ -11,13 +11,13 @@ internal class AsyncErrorConnectivityScenario(config: Configuration,
                                               context: Context) : Scenario(config, context) {
 
     override fun run() {
+        val delivery = createSlowDelivery(context)
+        config.delivery = delivery
         super.run()
-        val apiClient = createSlowErrorApiClient(context)
-        Bugsnag.setErrorReportApiClient(apiClient)
 
         writeErrorToStore(Bugsnag.getClient())
-        flushErrorStoreAsync(Bugsnag.getClient(), apiClient)
-        flushErrorStoreOnLaunch(Bugsnag.getClient(), apiClient)
+        flushErrorStoreAsync(Bugsnag.getClient())
+        flushErrorStoreOnLaunch(Bugsnag.getClient())
         Thread.sleep(50)
     }
 
diff --git a/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/AsyncErrorDoubleFlushScenario.kt b/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/AsyncErrorDoubleFlushScenario.kt
index 65b98b0090..4a0a66a230 100644
--- a/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/AsyncErrorDoubleFlushScenario.kt
+++ b/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/AsyncErrorDoubleFlushScenario.kt
@@ -11,13 +11,12 @@ internal class AsyncErrorDoubleFlushScenario(config: Configuration,
                                              context: Context) : Scenario(config, context) {
 
     override fun run() {
+        config.delivery = createSlowDelivery(context)
         super.run()
-        val apiClient = createSlowErrorApiClient(context)
-        Bugsnag.setErrorReportApiClient(apiClient)
 
         writeErrorToStore(Bugsnag.getClient())
-        flushErrorStoreAsync(Bugsnag.getClient(), apiClient)
-        flushErrorStoreAsync(Bugsnag.getClient(), apiClient)
+        flushErrorStoreAsync(Bugsnag.getClient())
+        flushErrorStoreAsync(Bugsnag.getClient())
         Thread.sleep(50)
     }
 
diff --git a/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/AsyncErrorLaunchScenario.kt b/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/AsyncErrorLaunchScenario.kt
index 87e5c8cf87..5be180e82d 100644
--- a/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/AsyncErrorLaunchScenario.kt
+++ b/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/AsyncErrorLaunchScenario.kt
@@ -11,13 +11,12 @@ internal class AsyncErrorLaunchScenario(config: Configuration,
                                         context: Context) : Scenario(config, context) {
 
     override fun run() {
+        config.delivery = createSlowDelivery(context)
         super.run()
-        val apiClient = createSlowErrorApiClient(context)
-        Bugsnag.setErrorReportApiClient(apiClient)
 
         writeErrorToStore(Bugsnag.getClient())
-        flushErrorStoreOnLaunch(Bugsnag.getClient(), apiClient)
-        flushErrorStoreAsync(Bugsnag.getClient(), apiClient)
+        flushErrorStoreOnLaunch(Bugsnag.getClient())
+        flushErrorStoreAsync(Bugsnag.getClient())
         Thread.sleep(50)
     }
 
diff --git a/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/CustomClientErrorFlushScenario.kt b/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/CustomClientErrorFlushScenario.kt
index f3f718a403..f58d75c0b1 100644
--- a/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/CustomClientErrorFlushScenario.kt
+++ b/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/CustomClientErrorFlushScenario.kt
@@ -3,7 +3,7 @@ package com.bugsnag.android.mazerunner.scenarios
 import android.content.Context
 import com.bugsnag.android.Bugsnag
 import com.bugsnag.android.Configuration
-import com.bugsnag.android.createDefaultErrorClient
+import com.bugsnag.android.createCustomHeaderDelivery
 
 /**
  * Sends an unhandled exception which is cached on disk to Bugsnag, then sent on a separate launch,
@@ -13,14 +13,12 @@ internal class CustomClientErrorFlushScenario(config: Configuration,
                                               context: Context) : Scenario(config, context) {
 
     override fun run() {
+        if ("DeliverReports" == eventMetaData) {
+            config.delivery = createCustomHeaderDelivery(context)
+        }
         super.run()
 
-        if ("DeliverReports" == eventMetaData) {
-            Bugsnag.setErrorReportApiClient { urlString, report, headers ->
-                headers["Custom-Client"] = "Hello World"
-                createDefaultErrorClient(context).postReport(urlString, report, headers)
-            }
-        } else {
+        if ("DeliverReports" != eventMetaData) {
             disableAllDelivery()
             throw RuntimeException("ReportCacheScenario")
         }
diff --git a/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/CustomClientErrorScenario.kt b/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/CustomClientErrorScenario.kt
index 1817553824..639319a340 100644
--- a/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/CustomClientErrorScenario.kt
+++ b/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/CustomClientErrorScenario.kt
@@ -3,7 +3,7 @@ package com.bugsnag.android.mazerunner.scenarios
 import android.content.Context
 import com.bugsnag.android.Bugsnag
 import com.bugsnag.android.Configuration
-import com.bugsnag.android.createDefaultErrorClient
+import com.bugsnag.android.createCustomHeaderDelivery
 
 /**
  * Sends a handled exception to Bugsnag using a custom API client which modifies the request.
@@ -12,12 +12,8 @@ internal class CustomClientErrorScenario(config: Configuration,
                                          context: Context) : Scenario(config, context) {
 
     override fun run() {
+        config.delivery = createCustomHeaderDelivery(context)
         super.run()
-
-        Bugsnag.setErrorReportApiClient { urlString, report, headers ->
-            headers["Custom-Client"] = "Hello World"
-            createDefaultErrorClient(context).postReport(urlString, report, headers)
-        }
         Bugsnag.notify(RuntimeException("Hello"))
     }
 
diff --git a/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/CustomClientSessionFlushScenario.kt b/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/CustomClientSessionFlushScenario.kt
index bd936019b6..f57b48a781 100644
--- a/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/CustomClientSessionFlushScenario.kt
+++ b/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/CustomClientSessionFlushScenario.kt
@@ -3,7 +3,8 @@ package com.bugsnag.android.mazerunner.scenarios
 import android.content.Context
 import com.bugsnag.android.Bugsnag
 import com.bugsnag.android.Configuration
-import com.bugsnag.android.createDefaultSessionClient
+import com.bugsnag.android.createCustomHeaderDelivery
+import com.bugsnag.android.createDefaultDelivery
 
 /**
  * Sends a session which is cached on disk to Bugsnag, then sent on a separate launch,
@@ -18,12 +19,7 @@ internal class CustomClientSessionFlushScenario(config: Configuration,
         if ("DeliverSessions" == eventMetaData) {
             // simulate activity lifecycle callback occurring before api client can be set
             Bugsnag.startSession()
-
-            Bugsnag.setSessionTrackingApiClient { urlString, report, headers ->
-                headers["Custom-Client"] = "Hello World"
-                val sessionClient = createDefaultSessionClient(context)
-                sessionClient.postSessionTrackingPayload(urlString, report, headers)
-            }
+            config.delivery = createCustomHeaderDelivery(context)
         } else {
             disableAllDelivery()
             Bugsnag.startSession()
diff --git a/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/CustomClientSessionScenario.kt b/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/CustomClientSessionScenario.kt
index 24593e358c..954e3143be 100644
--- a/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/CustomClientSessionScenario.kt
+++ b/mazerunner/src/main/java/com/bugsnag/android/mazerunner/scenarios/CustomClientSessionScenario.kt
@@ -3,7 +3,8 @@ package com.bugsnag.android.mazerunner.scenarios
 import android.content.Context
 import com.bugsnag.android.Bugsnag
 import com.bugsnag.android.Configuration
-import com.bugsnag.android.createDefaultSessionClient
+import com.bugsnag.android.createCustomHeaderDelivery
+import com.bugsnag.android.createDefaultDelivery
 
 /**
  * Sends a session using a custom API client which modifies the request.
@@ -12,14 +13,8 @@ internal class CustomClientSessionScenario(config: Configuration,
                                            context: Context) : Scenario(config, context) {
 
     override fun run() {
+        config.delivery = createCustomHeaderDelivery(context)
         super.run()
-
-        Bugsnag.setSessionTrackingApiClient { urlString, report, headers ->
-            headers["Custom-Client"] = "Hello World"
-            val sessionClient = createDefaultSessionClient(context)
-            sessionClient.postSessionTrackingPayload(urlString, report, headers)
-        }
-
         Bugsnag.startSession()
     }
 
diff --git a/sdk/src/androidTest/java/com/bugsnag/android/BreadcrumbLifecycleCrashTest.java b/sdk/src/androidTest/java/com/bugsnag/android/BreadcrumbLifecycleCrashTest.java
index 3223134e9f..f0f5cd6625 100644
--- a/sdk/src/androidTest/java/com/bugsnag/android/BreadcrumbLifecycleCrashTest.java
+++ b/sdk/src/androidTest/java/com/bugsnag/android/BreadcrumbLifecycleCrashTest.java
@@ -22,11 +22,10 @@ public class BreadcrumbLifecycleCrashTest {
      */
     @Before
     public void setUp() throws Exception {
-        Configuration configuration = new Configuration("api-key");
+        Configuration configuration = BugsnagTestUtils.generateConfiguration();
         Context context = InstrumentationRegistry.getContext();
         SessionStore sessionStore = new SessionStore(configuration, context);
-        SessionTrackingApiClient apiClient = BugsnagTestUtils.generateSessionTrackingApiClient();
-        sessionTracker = new SessionTracker(configuration, null, sessionStore, apiClient);
+        sessionTracker = new SessionTracker(configuration, null, sessionStore);
     }
 
     @Test
diff --git a/sdk/src/androidTest/java/com/bugsnag/android/BugsnagTestUtils.java b/sdk/src/androidTest/java/com/bugsnag/android/BugsnagTestUtils.java
index e4f38fe8aa..66b3c38c44 100644
--- a/sdk/src/androidTest/java/com/bugsnag/android/BugsnagTestUtils.java
+++ b/sdk/src/androidTest/java/com/bugsnag/android/BugsnagTestUtils.java
@@ -42,8 +42,7 @@ static SharedPreferences getSharedPrefs(Context context) {
 
     static Client generateClient() {
         Client client = new Client(InstrumentationRegistry.getContext(), "api-key");
-        client.setErrorReportApiClient(generateErrorReportApiClient());
-        client.setSessionTrackingApiClient(generateSessionTrackingApiClient());
+        client.config.setDelivery(generateDelivery());
         return client;
     }
 
@@ -52,12 +51,14 @@ static Session generateSession() {
     }
 
     static Configuration generateConfiguration() {
-        return new Configuration("test");
+        Configuration configuration = new Configuration("test");
+        configuration.setDelivery(generateDelivery());
+        return configuration;
     }
 
     static SessionTracker generateSessionTracker() {
         return new SessionTracker(generateConfiguration(), BugsnagTestUtils.generateClient(),
-            generateSessionStore(), generateSessionTrackingApiClient());
+            generateSessionStore());
     }
 
     @NonNull
@@ -89,4 +90,16 @@ public void postReport(String urlString,
             }
         };
     }
+
+    public static Delivery generateDelivery() {
+        return new Delivery() {
+            @Override
+            public void deliver(SessionTrackingPayload payload,
+                                Configuration config) throws DeliveryFailureException {}
+
+            @Override
+            public void deliver(Report report,
+                                Configuration config) throws DeliveryFailureException {}
+        };
+    }
 }
diff --git a/sdk/src/androidTest/java/com/bugsnag/android/ClientConfigTest.java b/sdk/src/androidTest/java/com/bugsnag/android/ClientConfigTest.java
index 875a1d571c..ef7e19a03e 100644
--- a/sdk/src/androidTest/java/com/bugsnag/android/ClientConfigTest.java
+++ b/sdk/src/androidTest/java/com/bugsnag/android/ClientConfigTest.java
@@ -3,6 +3,7 @@
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 
 import android.content.Context;
 import android.support.test.InstrumentationRegistry;
@@ -86,4 +87,26 @@ public void testSetSendThreads() throws Exception {
         assertFalse(config.getSendThreads());
     }
 
+    @Test
+    public void testDefaultClientDelivery() {
+        assertFalse(client.config.getDelivery() instanceof DeliveryCompat);
+    }
+
+    @Test
+    public void testCustomDeliveryOverride() {
+        Context context = InstrumentationRegistry.getContext();
+        config = BugsnagTestUtils.generateConfiguration();
+        Delivery customDelivery = new Delivery() {
+            @Override
+            public void deliver(SessionTrackingPayload payload,
+                                Configuration config) throws DeliveryFailureException {}
+
+            @Override
+            public void deliver(Report report,
+                                Configuration config) throws DeliveryFailureException {}
+        };
+        config.setDelivery(customDelivery);
+        client = new Client(context, config);
+        assertEquals(customDelivery, client.config.getDelivery());
+    }
 }
diff --git a/sdk/src/androidTest/java/com/bugsnag/android/ClientTest.java b/sdk/src/androidTest/java/com/bugsnag/android/ClientTest.java
index a14c781634..382caae06d 100644
--- a/sdk/src/androidTest/java/com/bugsnag/android/ClientTest.java
+++ b/sdk/src/androidTest/java/com/bugsnag/android/ClientTest.java
@@ -219,25 +219,6 @@ public void testFullManifestConfig() {
         assertEquals(true, newConfig.shouldAutoCaptureSessions());
     }
 
-    @Test
-    public void testSessionTrackerApiClient() throws Exception {
-        Client client = new Client(InstrumentationRegistry.getContext(), "api-key");
-        assertTrue(client.sessionTracker.getApiClient() instanceof DefaultHttpClient);
-
-        SessionTrackingApiClient customClient = new SessionTrackingApiClient() {
-            @Override
-            public void postSessionTrackingPayload(String urlString,
-                                                   SessionTrackingPayload payload,
-                                                   Map<String, String> headers)
-                throws NetworkException, BadResponseException {
-
-            }
-        };
-        client.setSessionTrackingApiClient(customClient);
-        assertFalse(client.sessionTracker.getApiClient() instanceof DefaultHttpClient);
-        assertEquals(customClient, client.sessionTracker.getApiClient());
-    }
-
     @Test
     public void testClientAddToTab() {
         Client client = generateClient();
diff --git a/sdk/src/androidTest/java/com/bugsnag/android/SessionTrackerTest.java b/sdk/src/androidTest/java/com/bugsnag/android/SessionTrackerTest.java
index 1eeb756fa1..4e6c7bba42 100644
--- a/sdk/src/androidTest/java/com/bugsnag/android/SessionTrackerTest.java
+++ b/sdk/src/androidTest/java/com/bugsnag/android/SessionTrackerTest.java
@@ -31,8 +31,9 @@ public class SessionTrackerTest {
     @Before
     public void setUp() throws Exception {
         configuration = new Configuration("test");
-        sessionTracker = new SessionTracker(configuration, generateClient(), generateSessionStore(),
-            generateSessionTrackingApiClient());
+        configuration.setDelivery(BugsnagTestUtils.generateDelivery());
+        sessionTracker
+            = new SessionTracker(configuration, generateClient(), generateSessionStore());
         configuration.setAutoCaptureSessions(true);
         user = new User();
     }
@@ -125,7 +126,7 @@ public void testBasicInForeground() throws Exception {
     public void testInForegroundDuration() throws Exception {
         long now = System.currentTimeMillis();
         sessionTracker = new SessionTracker(configuration, generateClient(),
-            0, generateSessionStore(), generateSessionTrackingApiClient());
+            0, generateSessionStore());
 
         sessionTracker.updateForegroundTracker(ACTIVITY_NAME, false, now);
         assertEquals(0, sessionTracker.getDurationInForegroundMs(now));
@@ -146,7 +147,7 @@ public void testInForegroundDuration() throws Exception {
     @Test
     public void testZeroSessionTimeout() throws Exception {
         sessionTracker = new SessionTracker(configuration, generateClient(),
-            0, generateSessionStore(), generateSessionTrackingApiClient());
+            0, generateSessionStore());
 
         long now = System.currentTimeMillis();
         sessionTracker.updateForegroundTracker(ACTIVITY_NAME, true, now);
@@ -161,7 +162,7 @@ public void testZeroSessionTimeout() throws Exception {
     @Test
     public void testSessionTimeout() throws Exception {
         sessionTracker = new SessionTracker(configuration, generateClient(),
-            100, generateSessionStore(), generateSessionTrackingApiClient());
+            100, generateSessionStore());
 
         long now = System.currentTimeMillis();
         sessionTracker.updateForegroundTracker(ACTIVITY_NAME, true, now);
diff --git a/sdk/src/main/java/com/bugsnag/android/Bugsnag.java b/sdk/src/main/java/com/bugsnag/android/Bugsnag.java
index 59e1ea8e05..17b8d4966c 100644
--- a/sdk/src/main/java/com/bugsnag/android/Bugsnag.java
+++ b/sdk/src/main/java/com/bugsnag/android/Bugsnag.java
@@ -298,7 +298,10 @@ public static void setUserName(final String name) {
      * https://docs.bugsnag.com/api/error-reporting/</a>
      *
      * @param errorReportApiClient the custom HTTP client implementation
+     *
+     * @deprecated use {@link Configuration#setDelivery(Delivery)} instead
      */
+    @Deprecated
     public static void setErrorReportApiClient(@NonNull ErrorReportApiClient errorReportApiClient) {
         getClient().setErrorReportApiClient(errorReportApiClient);
     }
@@ -312,11 +315,15 @@ public static void setErrorReportApiClient(@NonNull ErrorReportApiClient errorRe
      * the Bugsnag API.
      *
      * @param apiClient the custom HTTP client implementation
+     *
+     * @deprecated use {@link Configuration#setDelivery(Delivery)} instead
      */
+    @Deprecated
     public static void setSessionTrackingApiClient(@NonNull SessionTrackingApiClient apiClient) {
         getClient().setSessionTrackingApiClient(apiClient);
     }
 
+
     /**
      * Add a "before notify" callback, to execute code before every
      * report to Bugsnag.
diff --git a/sdk/src/main/java/com/bugsnag/android/Client.java b/sdk/src/main/java/com/bugsnag/android/Client.java
index c620678f6c..f6bc2b5406 100644
--- a/sdk/src/main/java/com/bugsnag/android/Client.java
+++ b/sdk/src/main/java/com/bugsnag/android/Client.java
@@ -76,8 +76,6 @@ public class Client extends Observable implements Observer {
 
     private final EventReceiver eventReceiver;
     final SessionTracker sessionTracker;
-    private ErrorReportApiClient errorReportApiClient;
-    private SessionTrackingApiClient sessionTrackingApiClient;
 
     /**
      * Initialize a Bugsnag client
@@ -126,12 +124,14 @@ public Client(@NonNull Context androidContext, @NonNull Configuration configurat
 
         ConnectivityManager cm =
             (ConnectivityManager) appContext.getSystemService(Context.CONNECTIVITY_SERVICE);
-        DefaultHttpClient defaultHttpClient = new DefaultHttpClient(cm);
-        errorReportApiClient = defaultHttpClient;
-        sessionTrackingApiClient = defaultHttpClient;
+
+        //noinspection ConstantConditions
+        if (configuration.getDelivery() == null) {
+            configuration.setDelivery(new DefaultDelivery(cm));
+        }
 
         sessionTracker =
-            new SessionTracker(configuration, this, sessionStore, sessionTrackingApiClient);
+            new SessionTracker(configuration, this, sessionStore);
         eventReceiver = new EventReceiver(this);
 
         // Set up and collect constant app and device diagnostics
@@ -164,8 +164,6 @@ public Client(@NonNull Context androidContext, @NonNull Configuration configurat
                 + "breadcrumbs on API Levels below 14.");
         }
 
-        errorReportApiClient = new DefaultHttpClient(cm);
-
         // populate from manifest (in the case where the constructor was called directly by the
         // User or no UUID was supplied)
         if (config.getBuildUUID() == null) {
@@ -211,7 +209,7 @@ public void run() {
 
 
         // Flush any on-disk errors
-        errorStore.flushOnLaunch(errorReportApiClient);
+        errorStore.flushOnLaunch();
     }
 
     private class ConnectivityChangeReceiver extends BroadcastReceiver {
@@ -223,7 +221,7 @@ public void onReceive(Context context, Intent intent) {
             boolean retryReports = networkInfo != null && networkInfo.isConnectedOrConnecting();
 
             if (retryReports) {
-                errorStore.flushAsync(errorReportApiClient);
+                errorStore.flushAsync();
             }
         }
     }
@@ -631,21 +629,36 @@ void setUserName(String name, boolean notify) {
         }
     }
 
+    DeliveryCompat getAndSetDeliveryCompat() {
+        Delivery current = config.getDelivery();
+
+        if (current instanceof DeliveryCompat) {
+            return (DeliveryCompat)current;
+        } else {
+            DeliveryCompat compat = new DeliveryCompat();
+            config.setDelivery(compat);
+            return compat;
+        }
+    }
+
     @SuppressWarnings("ConstantConditions")
+    @Deprecated
     void setErrorReportApiClient(@NonNull ErrorReportApiClient errorReportApiClient) {
         if (errorReportApiClient == null) {
             throw new IllegalArgumentException("ErrorReportApiClient cannot be null.");
         }
-        this.errorReportApiClient = errorReportApiClient;
+        DeliveryCompat compat = getAndSetDeliveryCompat();
+        compat.errorReportApiClient = errorReportApiClient;
     }
 
     @SuppressWarnings("ConstantConditions")
+    @Deprecated
     void setSessionTrackingApiClient(@NonNull SessionTrackingApiClient apiClient) {
         if (apiClient == null) {
             throw new IllegalArgumentException("SessionTrackingApiClient cannot be null.");
         }
-        this.sessionTrackingApiClient = apiClient;
-        sessionTracker.setApiClient(apiClient);
+        DeliveryCompat compat = getAndSetDeliveryCompat();
+        compat.sessionTrackingApiClient = apiClient;
     }
 
     /**
@@ -914,7 +927,7 @@ public void run() {
                 break;
             case ASYNC_WITH_CACHE:
                 errorStore.write(error);
-                errorStore.flushAsync(errorReportApiClient);
+                errorStore.flushAsync();
                 break;
             default:
                 break;
@@ -1237,16 +1250,21 @@ public void disableExceptionHandler() {
 
     void deliver(@NonNull Report report, @NonNull Error error) {
         try {
-            errorReportApiClient.postReport(config.getEndpoint(), report,
-                config.getErrorApiHeaders());
+            config.getDelivery().deliver(report, config);
             Logger.info("Sent 1 new error to Bugsnag");
-        } catch (NetworkException exception) {
-            Logger.info("Could not send error(s) to Bugsnag, saving to disk to send later");
-
-            // Save error to disk for later sending
-            errorStore.write(error);
-        } catch (BadResponseException exception) {
-            Logger.info("Bad response when sending data to Bugsnag");
+        } catch (DeliveryFailureException exception) {
+            switch (exception.reason) {
+                case CONNECTIVITY:
+                    Logger.info("Could not send error(s) to Bugsnag, saving to disk to send later");
+                    // Save error to disk for later sending
+                    errorStore.write(error);
+                    break;
+                case REQUEST_FAILURE:
+                    Logger.info("Bad response when sending data to Bugsnag");
+                    break;
+                default:
+                    break;
+            }
         } catch (Exception exception) {
             Logger.warn("Problem sending error to Bugsnag", exception);
         }
diff --git a/sdk/src/main/java/com/bugsnag/android/Configuration.java b/sdk/src/main/java/com/bugsnag/android/Configuration.java
index 2e84476482..e7be4effbb 100644
--- a/sdk/src/main/java/com/bugsnag/android/Configuration.java
+++ b/sdk/src/main/java/com/bugsnag/android/Configuration.java
@@ -8,7 +8,6 @@
 import java.util.Collection;
 import java.util.Date;
 import java.util.HashMap;
-import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Observable;
@@ -56,6 +55,8 @@ public class Configuration extends Observable implements Observer {
     private String codeBundleId;
     private String notifierType;
 
+    private Delivery delivery;
+
     /**
      * Construct a new Bugsnag configuration object
      *
@@ -494,7 +495,42 @@ String getNotifierType() {
         return notifierType;
     }
 
-    Map<String, String> getErrorApiHeaders() {
+    /**
+     * Retrieves the delivery used to make HTTP requests to Bugsnag.
+     *
+     * @return the current delivery
+     */
+    @NonNull
+    public Delivery getDelivery() {
+        return delivery;
+    }
+
+    /**
+     * Sets the delivery used to make HTTP requests to Bugsnag. A default implementation is
+     * provided, but you may wish to use your own implementation if you have requirements such
+     * as pinning SSL certificates, for example.
+     * <p>
+     * Any custom implementation must be capable of sending
+     * <a href="https://docs.bugsnag.com/api/error-reporting/">Error Reports</a>
+     * and <a href="https://docs.bugsnag.com/api/sessions/">Sessions</a> as
+     * documented at <a href="https://docs.bugsnag.com/api/">https://docs.bugsnag.com/api/</a>
+     *
+     * @param delivery the custom HTTP client implementation
+     */
+    public void setDelivery(@NonNull Delivery delivery) {
+        //noinspection ConstantConditions
+        if (delivery == null) {
+            throw new IllegalArgumentException("Delivery cannot be null");
+        }
+        this.delivery = delivery;
+    }
+
+    /**
+     * Supplies the headers which must be used in any request sent to the Error Reporting API.
+     *
+     * @return the HTTP headers
+     */
+    public Map<String, String> getErrorApiHeaders() {
         Map<String, String> map = new HashMap<>();
         map.put(HEADER_API_PAYLOAD_VERSION, "4.0");
         map.put(HEADER_API_KEY, apiKey);
@@ -502,7 +538,12 @@ Map<String, String> getErrorApiHeaders() {
         return map;
     }
 
-    Map<String, String> getSessionApiHeaders() {
+    /**
+     * Supplies the headers which must be used in any request sent to the Session Tracking API.
+     *
+     * @return the HTTP headers
+     */
+    public Map<String, String> getSessionApiHeaders() {
         Map<String, String> map = new HashMap<>();
         map.put(HEADER_API_PAYLOAD_VERSION, "1.0");
         map.put(HEADER_API_KEY, apiKey);
diff --git a/sdk/src/main/java/com/bugsnag/android/DefaultHttpClient.java b/sdk/src/main/java/com/bugsnag/android/DefaultDelivery.java
similarity index 56%
rename from sdk/src/main/java/com/bugsnag/android/DefaultHttpClient.java
rename to sdk/src/main/java/com/bugsnag/android/DefaultDelivery.java
index 348b65010b..5e5b2e2f19 100644
--- a/sdk/src/main/java/com/bugsnag/android/DefaultHttpClient.java
+++ b/sdk/src/main/java/com/bugsnag/android/DefaultDelivery.java
@@ -1,5 +1,8 @@
 package com.bugsnag.android;
 
+import static com.bugsnag.android.DeliveryFailureException.Reason.CONNECTIVITY;
+import static com.bugsnag.android.DeliveryFailureException.Reason.REQUEST_FAILURE;
+
 import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
 
@@ -10,48 +13,46 @@
 import java.net.URL;
 import java.util.Map;
 
-class DefaultHttpClient implements ErrorReportApiClient, SessionTrackingApiClient {
+class DefaultDelivery implements Delivery {
 
     private final ConnectivityManager connectivityManager;
 
-    DefaultHttpClient(ConnectivityManager connectivityManager) {
+    DefaultDelivery(ConnectivityManager connectivityManager) {
         this.connectivityManager = connectivityManager;
     }
 
     @Override
-    public void postReport(String urlString,
-                           Report report,
-                           Map<String, String> headers)
-        throws NetworkException, BadResponseException {
-
-        int status = makeRequest(urlString, report, headers);
+    public void deliver(SessionTrackingPayload payload,
+                        Configuration config) throws DeliveryFailureException {
+        String endpoint = config.getSessionEndpoint();
+        int status = deliver(endpoint, payload, config.getSessionApiHeaders());
 
-        if (status / 100 != 2) {
-            throw new BadResponseException(urlString, status);
+        if (status != 202) {
+            throw new DeliveryFailureException(REQUEST_FAILURE,
+                "Request failed with status " + status);
         } else {
-            Logger.info("Completed error API request");
+            Logger.info("Completed session tracking request");
         }
     }
 
     @Override
-    public void postSessionTrackingPayload(String urlString,
-                                           SessionTrackingPayload payload,
-                                           Map<String, String> headers)
-        throws NetworkException, BadResponseException {
-
-        int status = makeRequest(urlString, payload, headers);
+    public void deliver(Report report,
+                        Configuration config) throws DeliveryFailureException {
+        String endpoint = config.getEndpoint();
+        int status = deliver(endpoint, report, config.getErrorApiHeaders());
 
-        if (status != 202) {
-            throw new BadResponseException(urlString, status);
+        if (status / 100 != 2) {
+            throw new DeliveryFailureException(REQUEST_FAILURE,
+                "Request failed with status " + status);
         } else {
-            Logger.info("Completed session tracking request");
+            Logger.info("Completed error API request");
         }
     }
 
-    private int makeRequest(String urlString,
-                            JsonStream.Streamable streamable,
-                            Map<String, String> headers) throws NetworkException {
-        checkHasNetworkConnection(urlString);
+    int deliver(String urlString,
+                JsonStream.Streamable streamable,
+                Map<String, String> headers) throws DeliveryFailureException {
+        checkHasNetworkConnection();
         HttpURLConnection conn = null;
 
         try {
@@ -76,24 +77,22 @@ private int makeRequest(String urlString,
                 IOUtils.closeQuietly(out);
             }
 
-
             // End the request, get the response code
             return conn.getResponseCode();
         } catch (IOException exception) {
-            throw new NetworkException(urlString, exception);
+            throw new DeliveryFailureException(CONNECTIVITY,
+                "IOException encountered in request", exception);
         } finally {
             IOUtils.close(conn);
         }
     }
 
-    private void checkHasNetworkConnection(String urlString) throws NetworkException {
+    private void checkHasNetworkConnection() throws DeliveryFailureException {
         NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
 
         // conserve device battery by avoiding radio use
         if (!(activeNetworkInfo != null && activeNetworkInfo.isConnectedOrConnecting())) {
-            RuntimeException rex = new RuntimeException("No network connection available");
-            throw new NetworkException(urlString, rex);
+            throw new DeliveryFailureException(CONNECTIVITY, "No network connection available");
         }
     }
-
 }
diff --git a/sdk/src/main/java/com/bugsnag/android/Delivery.java b/sdk/src/main/java/com/bugsnag/android/Delivery.java
new file mode 100644
index 0000000000..de15adf3cb
--- /dev/null
+++ b/sdk/src/main/java/com/bugsnag/android/Delivery.java
@@ -0,0 +1,69 @@
+package com.bugsnag.android;
+
+
+/**
+ * Implementations of this interface deliver Error Reports and Sessions captured to the Bugsnag API.
+ * <p>
+ * A default {@link Delivery} implementation is provided as part of Bugsnag initialization,
+ * but you may wish to use your own implementation if you have requirements such
+ * as pinning SSL certificates, for example.
+ * <p>
+ * Any custom implementation must be capable of sending
+ * <a href="https://docs.bugsnag.com/api/error-reporting/">
+ * Error Reports</a> and <a href="https://docs.bugsnag.com/api/sessions/">Sessions</a> as
+ * documented at <a href="https://docs.bugsnag.com/api/">https://docs.bugsnag.com/api/</a>
+ *
+ * @see DefaultDelivery
+ */
+public interface Delivery {
+
+    /**
+     * Posts an array of sessions to the Bugsnag Session Tracking API.
+     * <p>
+     * This request must be delivered to the endpoint at {@link Configuration#getSessionEndpoint()},
+     * and contain the HTTP headers from {@link Configuration#getSessionApiHeaders()}.
+     * <p>
+     * If the response status code is not 202, then the implementation must throw
+     * {@link DeliveryFailureException} with a reason of
+     * {@link DeliveryFailureException.Reason#REQUEST_FAILURE}.
+     * <p>
+     * If the request could not be delivered due to connectivity issues, then the implementation
+     * must throw {@link DeliveryFailureException} with a reason of
+     * {@link DeliveryFailureException.Reason#CONNECTIVITY}, as this will cache the request for
+     * delivery at a future time.
+     * <p>
+     * See <a href="https://docs.bugsnag.com/api/sessions/">
+     * https://docs.bugsnag.com/api/sessions/</a>
+     *
+     * @param payload The session tracking payload
+     * @param config  The configuration by which this request will be sent
+     * @throws DeliveryFailureException when delivery does not receive a 202 status code.
+     */
+    void deliver(SessionTrackingPayload payload,
+                 Configuration config) throws DeliveryFailureException;
+
+    /**
+     * Posts an Error Report to the Bugsnag Error Reporting API.
+     * <p>
+     * This request must be delivered to the endpoint at {@link Configuration#getSessionEndpoint()},
+     * and contain the HTTP headers from {@link Configuration#getSessionApiHeaders()}.
+     * <p>
+     * If the response status code is not 2xx, then the implementation must throw
+     * {@link DeliveryFailureException} with a reason of
+     * {@link DeliveryFailureException.Reason#REQUEST_FAILURE}.
+     * <p>
+     * If the request could not be delivered due to connectivity issues, then the implementation
+     * must throw {@link DeliveryFailureException} with a reason of
+     * {@link DeliveryFailureException.Reason#CONNECTIVITY}, as this will cache the request for
+     * delivery at a future time.
+     * <p>
+     * See <a href="https://docs.bugsnag.com/api/error-reporting/">
+     * https://docs.bugsnag.com/api/error-reporting/</a>
+     *
+     * @param report The error report
+     * @param config The configuration by which this request will be sent
+     * @throws DeliveryFailureException when delivery does not receive a 2xx status code.
+     */
+    void deliver(Report report,
+                 Configuration config) throws DeliveryFailureException;
+}
diff --git a/sdk/src/main/java/com/bugsnag/android/DeliveryCompat.java b/sdk/src/main/java/com/bugsnag/android/DeliveryCompat.java
new file mode 100644
index 0000000000..e27bc809d0
--- /dev/null
+++ b/sdk/src/main/java/com/bugsnag/android/DeliveryCompat.java
@@ -0,0 +1,51 @@
+package com.bugsnag.android;
+
+import static com.bugsnag.android.DeliveryFailureException.Reason.CONNECTIVITY;
+import static com.bugsnag.android.DeliveryFailureException.Reason.REQUEST_FAILURE;
+
+/**
+ * A compatibility implementation of {@link Delivery} which wraps {@link ErrorReportApiClient} and
+ * {@link SessionTrackingApiClient}. This class allows for backwards compatibility for users still
+ * utilising the old API, and should be removed in the next major version.
+ */
+class DeliveryCompat implements Delivery {
+
+    volatile ErrorReportApiClient errorReportApiClient;
+    volatile SessionTrackingApiClient sessionTrackingApiClient;
+
+    @Override
+    public void deliver(SessionTrackingPayload payload,
+                        Configuration config) throws DeliveryFailureException {
+        if (sessionTrackingApiClient != null) {
+
+            try {
+                sessionTrackingApiClient.postSessionTrackingPayload(config.getSessionEndpoint(),
+                    payload, config.getSessionApiHeaders());
+            } catch (NetworkException | BadResponseException exception) {
+                throw convertException(exception);
+            }
+        }
+    }
+
+    @Override
+    public void deliver(Report report, Configuration config) throws DeliveryFailureException {
+        if (errorReportApiClient != null) {
+            try {
+                errorReportApiClient.postReport(config.getEndpoint(),
+                    report, config.getErrorApiHeaders());
+            } catch (NetworkException | BadResponseException exception) {
+                throw convertException(exception);
+            }
+        }
+    }
+
+    DeliveryFailureException convertException(Exception exception) {
+        if (exception instanceof NetworkException) {
+            return new DeliveryFailureException(CONNECTIVITY, exception.getMessage(), exception);
+        } else if (exception instanceof BadResponseException) {
+            return new DeliveryFailureException(REQUEST_FAILURE, exception.getMessage(), exception);
+        } else {
+            return null;
+        }
+    }
+}
diff --git a/sdk/src/main/java/com/bugsnag/android/DeliveryFailureException.java b/sdk/src/main/java/com/bugsnag/android/DeliveryFailureException.java
new file mode 100644
index 0000000000..d0a3321395
--- /dev/null
+++ b/sdk/src/main/java/com/bugsnag/android/DeliveryFailureException.java
@@ -0,0 +1,21 @@
+package com.bugsnag.android;
+
+public class DeliveryFailureException extends Exception {
+
+    enum Reason {
+        CONNECTIVITY,
+        REQUEST_FAILURE
+    }
+
+    final Reason reason;
+
+    public DeliveryFailureException(Reason reason, String msg) {
+        super(msg);
+        this.reason = reason;
+    }
+
+    public DeliveryFailureException(Reason reason, String msg, Throwable throwable) {
+        super(msg, throwable);
+        this.reason = reason;
+    }
+}
diff --git a/sdk/src/main/java/com/bugsnag/android/ErrorReportApiClient.java b/sdk/src/main/java/com/bugsnag/android/ErrorReportApiClient.java
index a67b05c43b..1c21bbb4eb 100644
--- a/sdk/src/main/java/com/bugsnag/android/ErrorReportApiClient.java
+++ b/sdk/src/main/java/com/bugsnag/android/ErrorReportApiClient.java
@@ -7,9 +7,10 @@
  * place of the default implementation, by calling
  * {@link Bugsnag#setErrorReportApiClient(ErrorReportApiClient)}
  *
- * @see DefaultHttpClient
+ * @deprecated use {@link Delivery} to send error reports
  */
 @SuppressWarnings("WeakerAccess")
+@Deprecated
 public interface ErrorReportApiClient {
 
     /**
diff --git a/sdk/src/main/java/com/bugsnag/android/ErrorStore.java b/sdk/src/main/java/com/bugsnag/android/ErrorStore.java
index c6f32711e4..aea0e50f18 100644
--- a/sdk/src/main/java/com/bugsnag/android/ErrorStore.java
+++ b/sdk/src/main/java/com/bugsnag/android/ErrorStore.java
@@ -50,11 +50,11 @@ public int compare(File lhs, File rhs) {
             "/bugsnag-errors/", 128, ERROR_REPORT_COMPARATOR);
     }
 
-    void flushOnLaunch(final ErrorReportApiClient errorReportApiClient) {
+    void flushOnLaunch() {
         final List<File> crashReports = findLaunchCrashReports();
 
         if (crashReports.isEmpty() || config.getLaunchCrashThresholdMs() == 0) {
-            flushAsync(errorReportApiClient); // if disabled or no startup crash, flush async
+            flushAsync(); // if disabled or no startup crash, flush async
         } else {
 
             // Block the main thread for a 2 second interval as the app may crash very soon.
@@ -66,7 +66,7 @@ void flushOnLaunch(final ErrorReportApiClient errorReportApiClient) {
             Async.run(new Runnable() {
                 @Override
                 public void run() {
-                    flushReports(crashReports, errorReportApiClient);
+                    flushReports(crashReports);
                     flushOnLaunchCompleted = true;
                 }
             });
@@ -88,7 +88,7 @@ public void run() {
     /**
      * Flush any on-disk errors to Bugsnag
      */
-    void flushAsync(final ErrorReportApiClient errorReportApiClient) {
+    void flushAsync() {
         if (storeDirectory == null) {
             return;
         }
@@ -97,7 +97,7 @@ void flushAsync(final ErrorReportApiClient errorReportApiClient) {
             Async.run(new Runnable() {
                 @Override
                 public void run() {
-                    flushReports(findStoredFiles(), errorReportApiClient);
+                    flushReports(findStoredFiles());
                 }
             });
         } catch (RejectedExecutionException exception) {
@@ -105,15 +105,14 @@ public void run() {
         }
     }
 
-    private void flushReports(Collection<File> storedReports,
-                              ErrorReportApiClient apiClient) {
+    private void flushReports(Collection<File> storedReports) {
         if (!storedReports.isEmpty() && semaphore.tryAcquire(1)) {
             try {
                 Logger.info(String.format(Locale.US,
                     "Sending %d saved error(s) to Bugsnag", storedReports.size()));
 
                 for (File errorFile : storedReports) {
-                    flushErrorReport(errorFile, apiClient);
+                    flushErrorReport(errorFile);
                 }
             } finally {
                 semaphore.release(1);
@@ -121,24 +120,36 @@ private void flushReports(Collection<File> storedReports,
         }
     }
 
-    private void flushErrorReport(File errorFile, ErrorReportApiClient errorReportApiClient) {
+    private void flushErrorReport(File errorFile) {
         try {
             Report report = new Report(config.getApiKey(), errorFile);
-            errorReportApiClient.postReport(config.getEndpoint(), report,
-                config.getErrorApiHeaders());
+            config.getDelivery().deliver(report, config);
 
             deleteStoredFiles(Collections.singleton(errorFile));
             Logger.info("Deleting sent error file " + errorFile.getName());
-        } catch (NetworkException exception) {
-            cancelQueuedFiles(Collections.singleton(errorFile));
-            Logger.warn("Could not send previously saved error(s)"
-                + " to Bugsnag, will try again later", exception);
+        } catch (DeliveryFailureException exception) {
+            switch (exception.reason) {
+                case CONNECTIVITY:
+                    cancelQueuedFiles(Collections.singleton(errorFile));
+                    Logger.warn("Could not send previously saved error(s)"
+                        + " to Bugsnag, will try again later", exception);
+                    break;
+                case REQUEST_FAILURE:
+                    handleRequestFailure(errorFile, exception);
+                    break;
+                default:
+                    break;
+            }
         } catch (Exception exception) {
-            deleteStoredFiles(Collections.singleton(errorFile));
-            Logger.warn("Problem sending unsent error from disk", exception);
+            handleRequestFailure(errorFile, exception);
         }
     }
 
+    private void handleRequestFailure(File errorFile, Exception exception) {
+        deleteStoredFiles(Collections.singleton(errorFile));
+        Logger.warn("Problem sending unsent error from disk", exception);
+    }
+
     boolean isLaunchCrashReport(File file) {
         return file.getName().endsWith("_startupcrash.json");
     }
diff --git a/sdk/src/main/java/com/bugsnag/android/SessionTracker.java b/sdk/src/main/java/com/bugsnag/android/SessionTracker.java
index b9d797be07..35a217f739 100644
--- a/sdk/src/main/java/com/bugsnag/android/SessionTracker.java
+++ b/sdk/src/main/java/com/bugsnag/android/SessionTracker.java
@@ -30,7 +30,6 @@ class SessionTracker implements Application.ActivityLifecycleCallbacks {
     private final long timeoutMs;
     private final Client client;
     private final SessionStore sessionStore;
-    private SessionTrackingApiClient apiClient;
 
     // This most recent time an Activity was stopped.
     private AtomicLong activityLastStoppedAtMs = new AtomicLong(0);
@@ -40,18 +39,16 @@ class SessionTracker implements Application.ActivityLifecycleCallbacks {
     private AtomicReference<Session> currentSession = new AtomicReference<>();
     private Semaphore flushingRequest = new Semaphore(1);
 
-    SessionTracker(Configuration configuration, Client client, SessionStore sessionStore,
-                   SessionTrackingApiClient apiClient) {
-        this(configuration, client, DEFAULT_TIMEOUT_MS, sessionStore, apiClient);
+    SessionTracker(Configuration configuration, Client client, SessionStore sessionStore) {
+        this(configuration, client, DEFAULT_TIMEOUT_MS, sessionStore);
     }
 
     SessionTracker(Configuration configuration, Client client, long timeoutMs,
-                   SessionStore sessionStore, SessionTrackingApiClient apiClient) {
+                   SessionStore sessionStore) {
         this.configuration = configuration;
         this.client = client;
         this.timeoutMs = timeoutMs;
         this.sessionStore = sessionStore;
-        this.apiClient = apiClient;
     }
 
     /**
@@ -69,14 +66,6 @@ void startNewSession(@NonNull Date date, @Nullable User user, boolean autoCaptur
         trackSessionIfNeeded(session);
     }
 
-    void setApiClient(SessionTrackingApiClient apiClient) {
-        this.apiClient = apiClient;
-    }
-
-    SessionTrackingApiClient getApiClient() {
-        return apiClient;
-    }
-
     /**
      * Determines whether or not a session should be tracked. If this is true, the session will be
      * stored and sent to the Bugsnag API, otherwise no action will occur in this method.
@@ -101,13 +90,19 @@ public void run() {
                             new SessionTrackingPayload(session, client.appData);
 
                         try {
-                            apiClient.postSessionTrackingPayload(endpoint, payload,
-                                configuration.getSessionApiHeaders());
-                        } catch (NetworkException exception) { // store for later sending
-                            Logger.info("Failed to post session payload");
-                            sessionStore.write(session);
-                        } catch (BadResponseException exception) { // drop bad data
-                            Logger.warn("Invalid session tracking payload", exception);
+                            configuration.getDelivery().deliver(payload, configuration);
+                        } catch (DeliveryFailureException exception) { // store for later sending
+                            switch (exception.reason) {
+                                case CONNECTIVITY:
+                                    Logger.info("Failed to post session payload");
+                                    sessionStore.write(session);
+                                    break;
+                                case REQUEST_FAILURE:
+                                    Logger.warn("Invalid session tracking payload", exception);
+                                    break;
+                                default:
+                                    break;
+                            }
                         }
                     }
                 });
@@ -168,16 +163,22 @@ void flushStoredSessions() {
 
                     //FUTURE:SM Reduce duplication here and above
                     try {
-                        final String endpoint = configuration.getSessionEndpoint();
-                        apiClient.postSessionTrackingPayload(endpoint, payload,
-                            configuration.getSessionApiHeaders());
-                        sessionStore.deleteStoredFiles(storedFiles);
-                    } catch (NetworkException exception) { // store for later sending
-                        sessionStore.cancelQueuedFiles(storedFiles);
-                        Logger.info("Failed to post stored session payload");
-                    } catch (BadResponseException exception) { // drop bad data
-                        Logger.warn("Invalid session tracking payload", exception);
+                        configuration.getDelivery().deliver(payload, configuration);
                         sessionStore.deleteStoredFiles(storedFiles);
+                    } catch (DeliveryFailureException exception) {
+                        switch (exception.reason) {
+                            case CONNECTIVITY: // store for later sending
+                                sessionStore.cancelQueuedFiles(storedFiles);
+                                Logger.info("Failed to post stored session payload");
+                                break;
+                            case REQUEST_FAILURE:
+                                // drop bad data
+                                Logger.warn("Invalid session tracking payload", exception);
+                                sessionStore.deleteStoredFiles(storedFiles);
+                                break;
+                            default:
+                                break;
+                        }
                     }
                 }
             } finally {
diff --git a/sdk/src/main/java/com/bugsnag/android/SessionTrackingApiClient.java b/sdk/src/main/java/com/bugsnag/android/SessionTrackingApiClient.java
index f82f05288f..cabd2d6b23 100644
--- a/sdk/src/main/java/com/bugsnag/android/SessionTrackingApiClient.java
+++ b/sdk/src/main/java/com/bugsnag/android/SessionTrackingApiClient.java
@@ -7,8 +7,9 @@
  * of this client can be used in place of the default implementation, by calling
  * {@link Bugsnag#setSessionTrackingApiClient(SessionTrackingApiClient)}
  *
- * @see DefaultHttpClient
+ * @deprecated use {@link Delivery} to send sessions
  */
+@Deprecated
 public interface SessionTrackingApiClient {
 
     /**