diff --git a/src/java/davmail/exception/DavMailAuthenticationException.java b/src/java/davmail/exception/DavMailAuthenticationException.java
index 259edc4b..c292ae77 100644
--- a/src/java/davmail/exception/DavMailAuthenticationException.java
+++ b/src/java/davmail/exception/DavMailAuthenticationException.java
@@ -18,6 +18,8 @@
  */
 package davmail.exception;
 
+import davmail.BundleMessage;
+
 /**
  * I18 AuthenticationException subclass.
  */
@@ -30,4 +32,14 @@ public class DavMailAuthenticationException extends DavMailException {
     public DavMailAuthenticationException(String key) {
         super(key);
     }
+
+    /**
+     * Create a DavMail authentication exception with the given BundleMessage key and arguments.
+     *
+     * @param key message key
+     */
+    public DavMailAuthenticationException(String key, Object... arguments) {
+         super(key, arguments);
+    }
+
 }
diff --git a/src/java/davmail/exchange/ExchangeSession.java b/src/java/davmail/exchange/ExchangeSession.java
index c358f344..288434c4 100644
--- a/src/java/davmail/exchange/ExchangeSession.java
+++ b/src/java/davmail/exchange/ExchangeSession.java
@@ -366,10 +366,10 @@ public class ExchangeSession {
                         logonMethod.addParameter(name, value);
                     }
                     // custom login form
-                    if ("txtUserName".equals(name)) {
-                        userNameInput = "txtUserName";
-                    } else if ("txtUserPass".equals(name)) {
-                        passwordInput = "txtUserPass";
+                    if ("txtUserName".equals(name) || "userid".equals(name)) {
+                        userNameInput = name;
+                    } else if ("txtUserPass".equals(name) || "pw".equals(name)) {
+                        passwordInput = name;
                     } else if ("addr".equals(name)) {
                         // this is not a logon form but a redirect form
                         HttpMethod newInitMethod = DavGatewayHttpClientFacade.executeFollowRedirects(httpClient, logonMethod);
@@ -450,6 +450,9 @@ public class ExchangeSession {
             throw new DavMailException("EXCEPTION_AUTHENTICATION_FORM_NOT_FOUND", initmethod.getURI());
         }
 
+        // make sure username and password fields are empty
+        ((PostMethod) logonMethod).removeParameter(userNameInput);
+        ((PostMethod) logonMethod).removeParameter(passwordInput);
         ((PostMethod) logonMethod).addParameter(userNameInput, userName);
         ((PostMethod) logonMethod).addParameter(passwordInput, password);
         ((PostMethod) logonMethod).addParameter("trusted", "4");
@@ -628,7 +631,7 @@ public class ExchangeSession {
             );
         } catch (IOException e) {
             LOGGER.error(e.getMessage());
-            throw new DavMailException("EXCEPTION_UNABLE_TO_GET_MAIL_FOLDER", mailPath);
+            throw new DavMailAuthenticationException("EXCEPTION_UNABLE_TO_GET_MAIL_FOLDER", mailPath);
         }
     }