diff --git a/lib/CompositionManager.php b/lib/CompositionManager.php
index 85d81f5..e0be254 100644
--- a/lib/CompositionManager.php
+++ b/lib/CompositionManager.php
@@ -465,6 +465,8 @@ class CompositionManager {
             ];
         }
 
+        $this->compositionStore->compositionDiscard($tenantId, $userId, $identifier);
+
         return [
             'identifier' => $identifier,
             'disposition' => 'sent'
diff --git a/tests/php/Unit/CompositionSynchronizationTest.php b/tests/php/Unit/CompositionSynchronizationTest.php
index 76daa8f..e8eae67 100644
--- a/tests/php/Unit/CompositionSynchronizationTest.php
+++ b/tests/php/Unit/CompositionSynchronizationTest.php
@@ -12,6 +12,8 @@ use KTXF\Mail\Entity\EntityMutableInterface;
 use KTXF\Mail\Object\MessagePropertiesMutableInterface;
 use KTXF\Mail\Service\ServiceBaseInterface;
 use KTXF\Mail\Service\ServiceEntityMutableInterface;
+use KTXF\Mail\Service\ServiceEntitySubmitInterface;
+use KTXF\Mail\Submission\EntitySubmitResult;
 use KTXF\Resource\Filter\IFilter;
 use KTXF\Resource\Identifier\CollectionIdentifier;
 use KTXF\Resource\Identifier\EntityIdentifier;
@@ -257,6 +259,62 @@ final class CompositionSynchronizationTest extends TestCase {
         ));
     }
 
+    public function testSendPurgesLocalCompositionOnSuccess(): void {
+        $this->stageComposition();
+        $properties = $this->createStub(MessagePropertiesMutableInterface::class);
+        $service = $this->submitService($properties);
+        $service->method('entitySubmit')->willReturn(new EntitySubmitResult(EntitySubmitResult::DISPOSITION_SENT));
+
+        $mailManager = $this->createStub(\KTXM\MailManager\Manager::class);
+        $mailManager->method('serviceFindByAddress')->willReturn($service);
+
+        $result = $this->compositionManager($mailManager)->send(
+            self::TENANT_ID,
+            self::USER_ID,
+            self::COMPOSITION_ID,
+            ['address' => 'sender@example.com'],
+            ['subject' => 'Sent draft'],
+            [],
+        );
+
+        $this->assertSame('sent', $result['disposition']);
+        $this->assertNull($this->compositionStore->compositionFetch(
+            self::TENANT_ID,
+            self::USER_ID,
+            self::COMPOSITION_ID,
+        ));
+    }
+
+    public function testSendFailureKeepsLocalComposition(): void {
+        $this->stageComposition();
+        $properties = $this->createStub(MessagePropertiesMutableInterface::class);
+        $service = $this->submitService($properties);
+        $service->method('entitySubmit')->willReturn(new EntitySubmitResult(
+            EntitySubmitResult::DISPOSITION_ERROR,
+            errorMessage: 'Transport unavailable',
+        ));
+
+        $mailManager = $this->createStub(\KTXM\MailManager\Manager::class);
+        $mailManager->method('serviceFindByAddress')->willReturn($service);
+
+        $result = $this->compositionManager($mailManager)->send(
+            self::TENANT_ID,
+            self::USER_ID,
+            self::COMPOSITION_ID,
+            ['address' => 'sender@example.com'],
+            ['subject' => 'Keep this draft'],
+            [],
+        );
+
+        $this->assertSame('error', $result['disposition']);
+        $this->assertSame('Transport unavailable', $result['error']['message']);
+        $this->assertNotNull($this->compositionStore->compositionFetch(
+            self::TENANT_ID,
+            self::USER_ID,
+            self::COMPOSITION_ID,
+        ));
+    }
+
     private function stageComposition(?string $remoteEntity = null): void {
         $saveComposition = static fn(): array => [
             'identifier' => self::COMPOSITION_ID,
@@ -292,6 +350,19 @@ final class CompositionSynchronizationTest extends TestCase {
         return $service;
     }
 
+    private function submitService(MessagePropertiesMutableInterface $properties): ServiceBaseInterface&ServiceEntitySubmitInterface&Stub {
+        $service = $this->createStubForIntersectionOfInterfaces([
+            ServiceBaseInterface::class,
+            ServiceEntitySubmitInterface::class,
+        ]);
+        $entity = $this->createStub(EntityMutableInterface::class);
+        $entity->method('getProperties')->willReturn($properties);
+        $service->method('identifier')->willReturn('service');
+        $service->method('getEnabled')->willReturn(true);
+        $service->method('entityFresh')->willReturn($entity);
+        return $service;
+    }
+
     private function compositionManager(\KTXM\MailManager\Manager $mailManager): CompositionManager {
         return new CompositionManager(
             container: $this->createStub(ContainerInterface::class),