Index: impl/src/java/org/sakaiproject/mailsender/logic/impl/ExternalLogicImpl.java
===================================================================
--- impl/src/java/org/sakaiproject/mailsender/logic/impl/ExternalLogicImpl.java	(revision 310401)
+++ impl/src/java/org/sakaiproject/mailsender/logic/impl/ExternalLogicImpl.java	(working copy)
@@ -348,12 +348,17 @@
           config = ConfigEntry.DEFAULT_CONFIG;
         }
 
-		ArrayList<EmailAddress> tos = new ArrayList<EmailAddress>();
+        StringBuilder emailAddresses= new StringBuilder();
+        ArrayList<EmailAddress> tos = new ArrayList<EmailAddress>();
         if (to != null)
         {
-            for (Entry<String, String> entry : to.entrySet())
+        	String sep = "";
+        	for (Entry<String, String> entry : to.entrySet())
             {
                 tos.add(new EmailAddress(entry.getKey(), entry.getValue()));
+                if(entry.getValue()!=null)
+                	emailAddresses.append(sep).append(entry.getKey());
+                sep = ",";
             }
         }
 
@@ -406,6 +411,10 @@
 		// add a special header for tracking
 		msg.addHeader("X-Mailer", "sakai-mailsender");
 		msg.addHeader("Content-Transfer-Encoding", "quoted-printable");
+		
+		if(emailAddresses!=null){
+			msg.addHeader("TO", emailAddresses.toString());
+		}
 
 		try
 		{