diff --git a/nachrichten-manager/src/main/java/de/ozgcloud/nachrichten/postfach/PostfachNachrichtMapper.java b/nachrichten-manager/src/main/java/de/ozgcloud/nachrichten/postfach/PostfachNachrichtMapper.java
index 8dc12e899041c5aba9a3125cb658971493c2dc2a..d7b6ca635a2f6940a7f28777a64ce0a8d6bc4089 100644
--- a/nachrichten-manager/src/main/java/de/ozgcloud/nachrichten/postfach/PostfachNachrichtMapper.java
+++ b/nachrichten-manager/src/main/java/de/ozgcloud/nachrichten/postfach/PostfachNachrichtMapper.java
@@ -90,12 +90,13 @@ public abstract class PostfachNachrichtMapper {
 	}
 
 	GrpcPostfachAddress buildGrpcPostfachAddress(Map<String, Object> postfachAddressMap) {
-		return GrpcPostfachAddress.newBuilder()
+		var postfachAddressBuilder = GrpcPostfachAddress.newBuilder()
 				.setType(MapUtils.getIntValue(postfachAddressMap, PostfachAddress.TYPE_FIELD))
 				.setVersion(MapUtils.getString(postfachAddressMap, PostfachAddress.VERSION_FIELD))
-				.setIdentifier(grpcObjectMapper.fromMap(postfachAddressMap))
-				.setServiceKontoType(MapUtils.getString(postfachAddressMap, PostfachAddress.SERVICEKONTO_TYPE_FIELD))
-				.build();
+				.setIdentifier(grpcObjectMapper.fromMap(postfachAddressMap));
+		Optional.ofNullable(MapUtils.getString(postfachAddressMap, PostfachAddress.SERVICEKONTO_TYPE_FIELD))
+				.ifPresent(postfachAddressBuilder::setServiceKontoType);
+		return postfachAddressBuilder.build();
 	}
 
 	PostfachNachricht fromMapToPostfachMail(Map<String, Object> mailMap) {
diff --git a/vorgang-manager-server/src/main/java/de/ozgcloud/vorgang/command/PersistPostfachNachrichtByCommandService.java b/vorgang-manager-server/src/main/java/de/ozgcloud/vorgang/command/PersistPostfachNachrichtByCommandService.java
index 0c5aedd9cf65651682383d7cc71723a192ce357e..2406a618b7ea9b82ae5515fd423cbc4e7a242aba 100644
--- a/vorgang-manager-server/src/main/java/de/ozgcloud/vorgang/command/PersistPostfachNachrichtByCommandService.java
+++ b/vorgang-manager-server/src/main/java/de/ozgcloud/vorgang/command/PersistPostfachNachrichtByCommandService.java
@@ -58,7 +58,9 @@ import de.ozgcloud.vorgang.callcontext.User;
 import de.ozgcloud.vorgang.files.FileService;
 import de.ozgcloud.vorgang.files.OzgFile;
 import de.ozgcloud.vorgang.files.UploadedFilesReference;
+
 import jakarta.activation.MimetypesFileTypeMap;
+
 import lombok.extern.log4j.Log4j2;
 
 /**
@@ -164,10 +166,14 @@ class PersistPostfachNachrichtByCommandService implements PersistPostfachNachric
 	}
 
 	private Map<String, Object> buildPostfachAddressMap(PostfachAddress postfachAddress) {
-		return Map.of(PostfachAddress.IDENTIFIER_FIELD, buildPostfachAddressIdentifierMap(postfachAddress),
-				PostfachAddress.VERSION_FIELD, postfachAddress.getVersion(),
-				PostfachAddress.TYPE_FIELD, postfachAddress.getType(),
-				PostfachAddress.SERVICEKONTO_TYPE_FIELD, postfachAddress.getServiceKontoType());
+		var resultMap = new HashMap<String, Object>();
+		resultMap.put(PostfachAddress.IDENTIFIER_FIELD, buildPostfachAddressIdentifierMap(postfachAddress));
+		resultMap.put(PostfachAddress.VERSION_FIELD, postfachAddress.getVersion());
+		resultMap.put(PostfachAddress.TYPE_FIELD, postfachAddress.getType());
+		Optional.ofNullable(postfachAddress.getServiceKontoType()).ifPresentOrElse(
+				serviceKontoType -> resultMap.put(PostfachAddress.SERVICEKONTO_TYPE_FIELD, serviceKontoType),
+				() -> LOG.warn("ServiceKontoType is null"));
+		return Collections.unmodifiableMap(resultMap);
 	}
 
 	private Map<String, Object> buildPostfachAddressIdentifierMap(PostfachAddress postfachAddress) {