diff --git a/src/java/davmail/exchange/ExchangeSession.java b/src/java/davmail/exchange/ExchangeSession.java
index 6a848d39..e7ec9c49 100644
--- a/src/java/davmail/exchange/ExchangeSession.java
+++ b/src/java/davmail/exchange/ExchangeSession.java
@@ -959,10 +959,10 @@ public abstract class ExchangeSession {
             Set<String> visibleRecipients = new HashSet<String>();
             Address[] recipients = mimeMessage.getAllRecipients();
             for (Address address : recipients) {
-                visibleRecipients.add(address.toString());
+                visibleRecipients.add(((InternetAddress)address).getAddress().toLowerCase());
             }
             for (String recipient : rcptToRecipients) {
-                if (!visibleRecipients.contains(recipient)) {
+                if (!visibleRecipients.contains(recipient.toLowerCase())) {
                     mimeMessage.addRecipient(javax.mail.Message.RecipientType.BCC, new InternetAddress(recipient));
                 }
             }
diff --git a/src/test/davmail/smtp/TestSmtp.java b/src/test/davmail/smtp/TestSmtp.java
index 9b8018bd..b02c0748 100644
--- a/src/test/davmail/smtp/TestSmtp.java
+++ b/src/test/davmail/smtp/TestSmtp.java
@@ -173,6 +173,15 @@ public class TestSmtp extends AbstractDavMailTestCase {
         sendAndCheckMessage(mimeMessage);
     }
 
+    public void testComplexToMessage() throws IOException, MessagingException, InterruptedException {
+        String body = "Test message";
+        MimeMessage mimeMessage = new MimeMessage((Session) null);
+        mimeMessage.addHeader("To", "nickname <"+Settings.getProperty("davmail.to")+ '>');
+        mimeMessage.setSubject("Test subject");
+        mimeMessage.setText(body);
+        sendAndCheckMessage(mimeMessage);
+    }
+
     public void testQuit() throws IOException {
        writeLine("QUIT");
         assertEquals("221 Closing connection", readLine());