diff --git a/src/java/davmail/exchange/ExchangeSession.java b/src/java/davmail/exchange/ExchangeSession.java
index a47711a0..209fdcc2 100644
--- a/src/java/davmail/exchange/ExchangeSession.java
+++ b/src/java/davmail/exchange/ExchangeSession.java
@@ -450,6 +450,7 @@ public class ExchangeSession {
         HttpMethod logonMethod = buildLogonMethod(httpClient, initmethod);
         ((PostMethod) logonMethod).addParameter(userNameInput, userName);
         ((PostMethod) logonMethod).addParameter(passwordInput, password);
+        ((PostMethod) logonMethod).addParameter("trusted", "4");
         logonMethod = DavGatewayHttpClientFacade.executeFollowRedirects(httpClient, logonMethod);
 
         // test form based authentication