diff --git a/src/main/java/de/bund/digitalservice/a2j/controller/SubscriberController.java b/src/main/java/de/bund/digitalservice/a2j/controller/SubscriberController.java
index 3d69d58..34e39ef 100644
--- a/src/main/java/de/bund/digitalservice/a2j/controller/SubscriberController.java
+++ b/src/main/java/de/bund/digitalservice/a2j/controller/SubscriberController.java
@@ -4,6 +4,8 @@
 import de.bund.digitalservice.a2j.service.subscriber.SubscriberService;
 import dev.fitko.fitconnect.api.domain.model.callback.NewSubmissionsCallback;
 import dev.fitko.fitconnect.api.domain.model.submission.SubmissionForPickup;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RestController;
@@ -17,13 +19,15 @@ public SubscriberController(SubscriberService service) {
     this.service = service;
   }
 
+  private static final Logger logger = LoggerFactory.getLogger(SubscriberController.class);
+
   @PostMapping("callbacks/fit-connect")
   public void newSubmission(@RequestBody NewSubmissionsCallback callback) {
     for (SubmissionForPickup submissionForPickup : callback.getSubmissions()) {
       try {
         service.pickUpSubmission(submissionForPickup);
       } catch (EgvpClientException e) {
-        throw new RuntimeException(e.getMessage());
+        logger.error("unable to propagate submission {}", submissionForPickup.getSubmissionId(), e);
       }
     }
   }
diff --git a/src/main/java/de/bund/digitalservice/a2j/repository/egvp/MessagesInTransitInMemoryRepository.java b/src/main/java/de/bund/digitalservice/a2j/repository/egvp/MessagesInTransitInMemoryRepository.java
index a8bde5e..a7ebf35 100644
--- a/src/main/java/de/bund/digitalservice/a2j/repository/egvp/MessagesInTransitInMemoryRepository.java
+++ b/src/main/java/de/bund/digitalservice/a2j/repository/egvp/MessagesInTransitInMemoryRepository.java
@@ -6,7 +6,7 @@
 
 @Component
 public class MessagesInTransitInMemoryRepository implements MessagesInTransitRepository {
-  public Set<MessageInTransit> messages = new HashSet<>();
+  private final Set<MessageInTransit> messages = new HashSet<>();
 
   public Set<MessageInTransit> getAll() {
     return messages;
diff --git a/src/main/java/de/bund/digitalservice/a2j/service/egvp/EgvpOutboxService.java b/src/main/java/de/bund/digitalservice/a2j/service/egvp/EgvpOutboxService.java
index 8a414d0..36227df 100644
--- a/src/main/java/de/bund/digitalservice/a2j/service/egvp/EgvpOutboxService.java
+++ b/src/main/java/de/bund/digitalservice/a2j/service/egvp/EgvpOutboxService.java
@@ -52,6 +52,7 @@ public void retrieveDeliveryStatus() {
           try {
             MessageDeliveryStatusResponse response =
                 this.client.checkMessageStatus(m.userId(), m.customId());
+
             if (response.delivered()) {
               deliveredMessages.add(m);
               // TODO send confirmation file to user
diff --git a/src/main/java/de/bund/digitalservice/a2j/service/egvp/client/EgvpClient.java b/src/main/java/de/bund/digitalservice/a2j/service/egvp/client/EgvpClient.java
index b8bd7da..7f95ee4 100644
--- a/src/main/java/de/bund/digitalservice/a2j/service/egvp/client/EgvpClient.java
+++ b/src/main/java/de/bund/digitalservice/a2j/service/egvp/client/EgvpClient.java
@@ -48,7 +48,7 @@ private <T> T invoke(Operation<T> operation) throws EgvpClientException {
           serverErrorException.getStatusCode().toString(), serverErrorException);
     } catch (RestClientException ex) {
 
-      throw new EgvpClientException(ex.getMessage().toString(), ex);
+      throw new EgvpClientException(ex.getMessage(), ex);
     }
   }
 }
diff --git a/src/test/java/de/bund/digitalservice/a2j/integration/EgvpClientIntegrationTest.java b/src/test/java/de/bund/digitalservice/a2j/integration/EgvpClientIntegrationTest.java
index a88e4cd..b484967 100644
--- a/src/test/java/de/bund/digitalservice/a2j/integration/EgvpClientIntegrationTest.java
+++ b/src/test/java/de/bund/digitalservice/a2j/integration/EgvpClientIntegrationTest.java
@@ -26,7 +26,7 @@
 // only extend with SpringExtension to avoid loading the whole Application context
 @ExtendWith(SpringExtension.class)
 @Tag("integration")
-public class EgvpClientIntegrationTest {
+class EgvpClientIntegrationTest {
 
   private EgvpClient client;
 
diff --git a/src/test/java/de/bund/digitalservice/a2j/integration/ReceiverIntegrationTest.java b/src/test/java/de/bund/digitalservice/a2j/integration/ReceiverIntegrationTest.java
index b70c8b8..b0e499c 100644
--- a/src/test/java/de/bund/digitalservice/a2j/integration/ReceiverIntegrationTest.java
+++ b/src/test/java/de/bund/digitalservice/a2j/integration/ReceiverIntegrationTest.java
@@ -84,7 +84,7 @@ void shouldSecureCallbackWithAuthorization() throws EgvpClientException {
   }
 
   @Test
-  void shouldSecureCallbackWithoutAuthorization() throws EgvpClientException {
+  void shouldSecureCallbackWithoutAuthorization() {
     when(senderClient.validateCallback(any(), any(), any(), any()))
         .thenReturn(ValidationResult.error("invalid callback"));
 
diff --git a/src/test/java/de/bund/digitalservice/a2j/service/egvp/EgvpOutboxServiceTest.java b/src/test/java/de/bund/digitalservice/a2j/service/egvp/EgvpOutboxServiceTest.java
index 0b14be5..bfc0f28 100644
--- a/src/test/java/de/bund/digitalservice/a2j/service/egvp/EgvpOutboxServiceTest.java
+++ b/src/test/java/de/bund/digitalservice/a2j/service/egvp/EgvpOutboxServiceTest.java
@@ -13,12 +13,12 @@
 import org.springframework.test.context.junit.jupiter.SpringExtension;
 
 @ExtendWith(SpringExtension.class)
-public class EgvpOutboxServiceTest {
+class EgvpOutboxServiceTest {
 
   @MockBean private EgvpClient egvpClient;
 
   @Test
-  public void sendMessageTest() throws EgvpClientException {
+  void sendMessageTest() throws EgvpClientException {
     MessagesInTransitRepository repo = new MessagesInTransitInMemoryRepository();
     EgvpOutboxService service = new EgvpOutboxService(egvpClient, repo);
 
@@ -40,7 +40,7 @@ public void sendMessageTest() throws EgvpClientException {
   }
 
   @Test
-  public void retrieveDeliveredMessage() throws EgvpClientException {
+  void retrieveDeliveredMessage() throws EgvpClientException {
     MessagesInTransitRepository repo = new MessagesInTransitInMemoryRepository();
     repo.add(new MessageInTransit("userId", "customId", "mailboxId"));
 
@@ -54,7 +54,7 @@ public void retrieveDeliveredMessage() throws EgvpClientException {
   }
 
   @Test
-  public void keepPendingMessagesInTransit() throws EgvpClientException {
+  void keepPendingMessagesInTransit() throws EgvpClientException {
     MessagesInTransitRepository repo = new MessagesInTransitInMemoryRepository();
     MessageInTransit msg = new MessageInTransit("userId", "customId", "mailboxId");
     repo.add(msg);
@@ -68,7 +68,7 @@ public void keepPendingMessagesInTransit() throws EgvpClientException {
   }
 
   @Test
-  public void deleteInTransitMessagesOnFailure() throws EgvpClientException {
+  void deleteInTransitMessagesOnFailure() throws EgvpClientException {
     MessagesInTransitRepository repo = new MessagesInTransitInMemoryRepository();
     MessageInTransit msg = new MessageInTransit("userId", "customId", "mailboxId");
     repo.add(msg);
diff --git a/src/test/java/de/bund/digitalservice/a2j/service/subscriber/FitConnectSubscriberServiceTest.java b/src/test/java/de/bund/digitalservice/a2j/service/subscriber/FitConnectSubscriberServiceTest.java
index 098f55a..854479c 100644
--- a/src/test/java/de/bund/digitalservice/a2j/service/subscriber/FitConnectSubscriberServiceTest.java
+++ b/src/test/java/de/bund/digitalservice/a2j/service/subscriber/FitConnectSubscriberServiceTest.java
@@ -9,7 +9,6 @@
 import dev.fitko.fitconnect.api.domain.model.submission.SubmissionForPickup;
 import dev.fitko.fitconnect.api.domain.subscriber.ReceivedSubmission;
 import dev.fitko.fitconnect.client.SubscriberClient;
-import java.io.IOException;
 import java.util.UUID;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -35,7 +34,7 @@ void setup() {
   }
 
   @Test
-  void testPickUpSubmission() throws IOException, EgvpClientException {
+  void testPickUpSubmission() throws EgvpClientException {
     when(client.requestSubmission(submissionForPickup)).thenReturn(receivedSubmission);
     UUID caseId = UUID.randomUUID();
     when(receivedSubmission.getSubmissionId()).thenReturn(UUID.randomUUID());