this patch handles sun specific private extension and possibly cannot be submitted to dojo community
Index: dojo-release-1.3.2-src/dojox/xmpp/xmppSession.js
===================================================================
--- dojo-release-1.3.2-src.orig/dojox/xmpp/xmppSession.js	2009-09-04 11:21:11.000000000 -0700
+++ dojo-release-1.3.2-src/dojox/xmpp/xmppSession.js	2009-09-04 11:22:42.000000000 -0700
@@ -490,6 +490,7 @@
 			}
 			var req = new dojox.string.Builder(dojox.xmpp.util.createElement("iq",props,false));
 			req.append(dojox.xmpp.util.createElement("query",{xmlns: "jabber:iq:roster"},true));
+                        req.append(dojox.xmpp.util.createElement("x",{xmlns: "sun:im:xmpp:roster:extra"},true));
 			req.append("</iq>");
 
 			var def = this.dispatchPacket(req,"iq", props.id);
@@ -513,6 +514,7 @@
 				name: elem.getAttribute('name'),
 				jid: elem.getAttribute('jid'),
 				groups: [],
+                                email: [],
 				status: dojox.xmpp.presence.SUBSCRIPTION_NONE,
 				substatus: dojox.xmpp.presence.SUBSCRIPTION_SUBSTATUS_NONE
 			//	displayToUser: false
@@ -529,6 +531,22 @@
 				if (n.nodeName=='group' && n.hasChildNodes()){
 					re.groups.push(n.firstChild.nodeValue);
 				}
+                                if (n.nodeName=='x' &&
+                                    n.getAttribute('xmlns')=="sun:im:xmpp:roster:extra" &&
+                                    n.hasChildNodes())
+                                {
+                                    for(var k=0; k<n.childNodes.length;k++){
+                                        var p = n.childNodes[k];
+                                        if (p.nodeName=='property' &&
+                                            p.getAttribute('name') == "mail" &&
+                                            p.hasChildNodes())
+                                        {
+                                            for(var m=0; m<p.childNodes.length;m++){
+                                                re.email.push(p.childNodes[m].firstChild.nodeValue);
+                                            }
+                                        }
+                                    }
+                                }
 			} 
 
 			if (elem.getAttribute('subscription')){