diff --git a/calendar/base/content/calendar-item-editing.js b/calendar/base/content/calendar-item-editing.js
index 63c323bdc38..5c6ceddc67d 100644
--- a/calendar/base/content/calendar-item-editing.js
+++ b/calendar/base/content/calendar-item-editing.js
@@ -510,7 +510,7 @@ function checkAndSendItipMessage(aItem, aOpType, aOriginalItem) {
 
             var itipItem = Components.classes["@mozilla.org/calendar/itip-item;1"]
                                      .createInstance(Components.interfaces.calIItipItem);
-            itipItem.init(aItem.icalString);
+            itipItem.init(calGetSerializedItem(aItem));
             itipItem.targetCalendar = aItem.calendar;
             itipItem.autoResponse = Components.interfaces.calIItipItem.USER;
             itipItem.responseMethod = "REPLY";
@@ -530,7 +530,7 @@ function checkAndSendItipMessage(aItem, aOpType, aOriginalItem) {
         }
 
         for each (var att in itemAtt) {
-            if (att.id in attMap) {
+            if (att.id.toLowerCase() in attMap) {
                 // Attendee was in original item.
                 delete attMap[att.id.toLowerCase()];
             }
@@ -586,6 +586,9 @@ function checkAndSendItipMessage(aItem, aOpType, aOriginalItem) {
 }
 
 function calSendItipMessage(aItem, aMethod, aRecipientsList) {
+    if (aRecipientsList.length == 0) {
+        return;
+    }
     if ((aItem.calendar instanceof Components.interfaces.calISchedulingSupport) &&
         aItem.calendar.canNotify(aMethod, aItem)) {
         return; // provider will handle that
@@ -600,16 +603,15 @@ function calSendItipMessage(aItem, aMethod, aRecipientsList) {
     var item = aItem.clone();
 
     // We fake Sequence ID support.
-    item.setProperty("METHOD", aMethod);
     item.setProperty("SEQUENCE", item.generation);
 
     // Initialize and set our properties on the item
-    itipItem.init(item.icalString);
+    itipItem.init(calGetSerializedItem(item));
+    itipItem.responseMethod = aMethod;
     itipItem.targetCalendar = item.calendar;
     itipItem.autoResponse = Components.interfaces.calIItipItem.USER;
     // XXX I don't know whether the below are used at all, since we don't use the itip processor
     itipItem.isSend = true;
-    itipItem.receivedMethod = aMethod;
 
     // Get ourselves some default text - when we handle organizer properly
     // We'll need a way to configure the Common Name attribute and we should
@@ -641,3 +643,10 @@ function calSendItipMessage(aItem, aMethod, aRecipientsList) {
     transport.sendItems(aRecipientsList.length, aRecipientsList, subject, body, itipItem);
 }
 
+function calGetSerializedItem(aItem) {
+    var serializer = Components.classes["@mozilla.org/calendar/ics-serializer;1"]
+                               .createInstance(Components.interfaces.calIIcsSerializer);
+    serializer.addItems([aItem], 1);
+    return serializer.serializeToString();
+}
+
diff --git a/calendar/base/src/calEvent.js b/calendar/base/src/calEvent.js
index 894198218b3..a0f1630d48c 100644
--- a/calendar/base/src/calEvent.js
+++ b/calendar/base/src/calEvent.js
@@ -140,9 +140,6 @@ calEvent.prototype = {
     get icalString() {
         var calcomp = getIcsService().createIcalComponent("VCALENDAR");
         calSetProdidVersion(calcomp);
-        if (this.hasProperty("METHOD")) {
-            calcomp.method = this.getProperty("METHOD");
-        }
         calcomp.addSubcomponent(this.icalComponent);
         return calcomp.serializeToICS();
     },
diff --git a/calendar/base/src/calItemBase.js b/calendar/base/src/calItemBase.js
index 83fc4cf2a25..a24f6b0110f 100644
--- a/calendar/base/src/calItemBase.js
+++ b/calendar/base/src/calItemBase.js
@@ -558,7 +558,6 @@ calItemBase.prototype = {
         "LAST-MODIFIED": true,
         "SUMMARY": true,
         "PRIORITY": true,
-        "METHOD": true,
         "STATUS": true,
         "CLASS": true,
         "DTSTAMP": true,
diff --git a/calendar/itip/calItipEmailTransport.js b/calendar/itip/calItipEmailTransport.js
index 4b97db683ad..5b4b1dfa39d 100644
--- a/calendar/itip/calItipEmailTransport.js
+++ b/calendar/itip/calItipEmailTransport.js
@@ -317,20 +317,13 @@ calItipEmailTransport.prototype = {
             }
 
             var itemList = aItem.getItemList({});
-            var calText = "";
-            for (var i = 0; i < itemList.length; i++) {
-                var item = itemList[i].clone();
-                // This is a workaround until bug 353369 is fixed.
-                // Without it, we cannot roundtrip the METHOD property, so we must
-                // re-add it to the ICS data as we serialize it.
-                //
-                // Look at the implicit assumption in the code at:
-                // http://lxr.mozilla.org/seamonkey/source/calendar/base/src/calEvent.js#162
-                // and it's easy to see why.
-                item.setProperty("METHOD", aItem.responseMethod);
-                // xxx todo: should we consider to include exceptional/overridden items?
-                calText += item.icalString;
-            }
+            var serializer = Components.classes["@mozilla.org/calendar/ics-serializer;1"]
+                                       .createInstance(Components.interfaces.calIIcsSerializer);
+            serializer.addItems(itemList, itemList.length);
+            var methodProp = getIcsService().createIcalProperty("METHOD");
+            methodProp.value = aItem.responseMethod;
+            serializer.addProperty(methodProp);
+            var calText = serializer.serializeToString();
             var utf8CalText = encodeUTF8(calText);
 
             // Home-grown mail composition; I'd love to use nsIMimeEmitter, but it's not clear to me whether