diff --git a/pom.xml b/pom.xml
index bb6589b..4f67c65 100644
--- a/pom.xml
+++ b/pom.xml
@@ -18,6 +18,7 @@
 	<properties>
 		<java-version>1.8</java-version>
 		<enunciate.version>2.14.0</enunciate.version>
+		<jackson.version>2.8.11</jackson.version>
 		<webappDirectory>${project.build.directory}/${project.build.finalName}</webappDirectory>
 		<enunciate.version>2.14.0</enunciate.version>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
diff --git a/src/main/java/org/gcube/portal/social/networking/ws/methods/v2/Notifications.java b/src/main/java/org/gcube/portal/social/networking/ws/methods/v2/Notifications.java
index 1c04a81..a86574c 100644
--- a/src/main/java/org/gcube/portal/social/networking/ws/methods/v2/Notifications.java
+++ b/src/main/java/org/gcube/portal/social/networking/ws/methods/v2/Notifications.java
@@ -185,6 +185,7 @@ public class Notifications {
 
 		Caller caller = AuthorizationProvider.instance.get();
 		String context  = ScopeProvider.instance.get();
+		String username = caller.getClient().getId();
 
 		if (!message.getType().getNotificationClass().isInstance(message.getBean())) {
 			//invalid call
@@ -196,7 +197,7 @@ public class Notifications {
 		
 		try{
 			SocialNetworkingSite site = SocialNetworkingSiteFinder.getSocialNetworkingSiteFromScope(context);
-			GCubeUser senderUser = UserManagerWSBuilder.getInstance().getUserManager().getUserByEmail(LiferayJSONWsCredentials.getSingleton().getUser());
+			GCubeUser senderUser = UserManagerWSBuilder.getInstance().getUserManager().getUserByUsername(username);			
 			SocialNetworkingUser user = new SocialNetworkingUser(senderUser.getUsername(), senderUser.getEmail(), senderUser.getFullname(), senderUser.getUserAvatarURL());
 			NotificationsManager nm = new ApplicationNotificationsManager(UserManagerWSBuilder.getInstance().getUserManager(), site, context, user);		
 			switch (message.getType()) {