diff --git a/src/java/davmail/exchange/ExchangeSession.java b/src/java/davmail/exchange/ExchangeSession.java
index 8a8b6569..42df170b 100644
--- a/src/java/davmail/exchange/ExchangeSession.java
+++ b/src/java/davmail/exchange/ExchangeSession.java
@@ -2245,12 +2245,7 @@ public abstract class ExchangeSession {
      * @return list of calendar messages as Event objects
      * @throws IOException on error
      */
-    public List<Event> getEventMessages(String folderPath) throws IOException {
-        return searchEvents(folderPath, ITEM_PROPERTIES,
-                and(or(isEqualTo("outlookmessageclass", "IPM.Schedule.Meeting.Request"),
-                        isEqualTo("outlookmessageclass", "IPM.Schedule.Meeting.Canceled")),
-                        or(isNull("processed"), isFalse("processed"))));
-    }
+    public abstract List<Event> getEventMessages(String folderPath) throws IOException;
 
     /**
      * Search calendar events in provided folder.
diff --git a/src/java/davmail/exchange/dav/DavExchangeSession.java b/src/java/davmail/exchange/dav/DavExchangeSession.java
index 805032b5..f52a5dd2 100644
--- a/src/java/davmail/exchange/dav/DavExchangeSession.java
+++ b/src/java/davmail/exchange/dav/DavExchangeSession.java
@@ -1684,6 +1684,17 @@ public class DavExchangeSession extends ExchangeSession {
         return contacts;
     }
 
+    /**
+     * @inheritDoc
+     */
+    @Override
+    public List<ExchangeSession.Event> getEventMessages(String folderPath) throws IOException {
+        return searchEvents(folderPath, ITEM_PROPERTIES,
+                and(isEqualTo("contentclass", "urn:content-classes:calendarmessage"),
+                        or(isNull("processed"), isFalse("processed"))));
+    }
+
+
     @Override
     public List<ExchangeSession.Event> searchEvents(String folderPath, Set<String> attributes, Condition condition) throws IOException {
         List<ExchangeSession.Event> events = new ArrayList<ExchangeSession.Event>();
diff --git a/src/java/davmail/exchange/ews/EwsExchangeSession.java b/src/java/davmail/exchange/ews/EwsExchangeSession.java
index e5403893..83f0fa71 100644
--- a/src/java/davmail/exchange/ews/EwsExchangeSession.java
+++ b/src/java/davmail/exchange/ews/EwsExchangeSession.java
@@ -1079,6 +1079,13 @@ public class EwsExchangeSession extends ExchangeSession {
         return contacts;
     }
 
+    @Override
+    public List<ExchangeSession.Event> getEventMessages(String folderPath) throws IOException {
+        return searchEvents(folderPath, ITEM_PROPERTIES,
+                and(startsWith("outlookmessageclass", "IPM.Schedule.Meeting."),
+                        or(isNull("processed"), isFalse("processed"))));
+    }
+
     @Override
     public List<ExchangeSession.Event> searchEvents(String folderPath, Set<String> attributes, Condition condition) throws IOException {
         List<ExchangeSession.Event> events = new ArrayList<ExchangeSession.Event>();