diff --git a/mozilla/mailnews/base/search/src/nsMsgFilterList.cpp b/mozilla/mailnews/base/search/src/nsMsgFilterList.cpp
index 982b4b586fd..e62de4c75c5 100644
--- a/mozilla/mailnews/base/search/src/nsMsgFilterList.cpp
+++ b/mozilla/mailnews/base/search/src/nsMsgFilterList.cpp
@@ -73,6 +73,7 @@ nsMsgFilterList::nsMsgFilterList() :
 
   m_loggingEnabled = PR_FALSE;
   m_startWritingToBuffer = PR_FALSE; 
+  m_temporaryList = PR_FALSE;
   m_curFilter = nsnull;
   m_arbitraryHeaders.SetLength(0);
 }
@@ -963,7 +964,8 @@ nsMsgFilterList::RemoveFilter(nsIMsgFilter *aFilter)
 nsresult nsMsgFilterList::InsertFilterAt(PRUint32 filterIndex, nsIMsgFilter *aFilter)
 {
   nsMsgFilter *filter = NS_STATIC_CAST(nsMsgFilter *, aFilter);
-  filter->SetFilterList(this);
+  if (!m_temporaryList)
+    filter->SetFilterList(this);
   m_filters->InsertElementAt(aFilter, filterIndex);
   return NS_OK;
 }
diff --git a/mozilla/mailnews/base/search/src/nsMsgFilterList.h b/mozilla/mailnews/base/search/src/nsMsgFilterList.h
index 053bc049705..b83cabecae8 100644
--- a/mozilla/mailnews/base/search/src/nsMsgFilterList.h
+++ b/mozilla/mailnews/base/search/src/nsMsgFilterList.h
@@ -74,6 +74,8 @@ public:
   nsresult Close();
   nsresult LoadTextFilters(nsIOFileStream *aStream);
 
+  PRBool m_temporaryList;
+
 protected:
   // type-safe accessor when you really have to have an nsMsgFilter
   nsresult GetMsgFilterAt(PRUint32 filterIndex, nsMsgFilter **filter);
diff --git a/mozilla/mailnews/base/search/src/nsMsgFilterService.cpp b/mozilla/mailnews/base/search/src/nsMsgFilterService.cpp
index 8be9300912b..6d023c87881 100644
--- a/mozilla/mailnews/base/search/src/nsMsgFilterService.cpp
+++ b/mozilla/mailnews/base/search/src/nsMsgFilterService.cpp
@@ -716,14 +716,12 @@ nsresult nsMsgFilterAfterTheFact::ApplyFilter()
 NS_IMETHODIMP nsMsgFilterService::GetTempFilterList(nsIMsgFolder *aFolder, nsIMsgFilterList **aFilterList)
 {
   NS_ENSURE_ARG_POINTER(aFilterList);
-  *aFilterList = new nsMsgFilterList;
-  if (*aFilterList)
-  {
-    (*aFilterList)->SetFolder(aFolder);
-    NS_ADDREF(*aFilterList);
-    return NS_OK;
-  }
-  return NS_ERROR_OUT_OF_MEMORY;
+  nsMsgFilterList *filterList = new nsMsgFilterList;
+  NS_ENSURE_TRUE(filterList, NS_ERROR_OUT_OF_MEMORY);
+  NS_ADDREF(*aFilterList = filterList);
+  (*aFilterList)->SetFolder(aFolder);
+  filterList->m_temporaryList = PR_TRUE;
+  return NS_OK;
 }
 
 NS_IMETHODIMP nsMsgFilterService::ApplyFiltersToFolders(nsIMsgFilterList *aFilterList, nsISupportsArray *aFolders, nsIMsgWindow *aMsgWindow)