--- a/mailnews/base/src/nsMsgFolderDataSource.cpp
+++ b/mailnews/base/src/nsMsgFolderDataSource.cpp
@@ -543,25 +543,25 @@ nsMsgFolderDataSource::getFolderArcLabel
   aArcs.AppendObject(kNC_CanSearchMessages);
 
   return NS_OK;
 }
 
 NS_IMETHODIMP
 nsMsgFolderDataSource::GetAllResources(nsISimpleEnumerator** aCursor)
 {
-  NS_NOTYETIMPLEMENTED("sorry!");
+  MOZ_ASSERT_UNREACHABLE("sorry!");
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
 NS_IMETHODIMP
 nsMsgFolderDataSource::GetAllCmds(nsIRDFResource* source,
                                       nsISimpleEnumerator/*<nsIRDFResource>*/** commands)
 {
-  NS_NOTYETIMPLEMENTED("no one actually uses me");
+  MOZ_ASSERT_UNREACHABLE("no one actually uses me");
   nsresult rv;
 
   nsCOMPtr<nsIMsgFolder> folder(do_QueryInterface(source, &rv));
   if (NS_FAILED(rv)) return rv;
 
   nsCOMPtr<nsIMutableArray> cmds =
     do_CreateInstance(NS_ARRAY_CONTRACTID);
   NS_ENSURE_STATE(cmds);

--- a/mailnews/base/src/nsSubscribeDataSource.cpp
+++ b/mailnews/base/src/nsSubscribeDataSource.cpp
@@ -554,17 +554,17 @@ nsSubscribeDataSource::ArcLabelsOut(nsIR
     }
 
     return NS_NewArrayEnumerator(labels, array);
 }
 
 NS_IMETHODIMP
 nsSubscribeDataSource::GetAllResources(nsISimpleEnumerator** aCursor)
 {
-	NS_NOTYETIMPLEMENTED("sorry!");
+	MOZ_ASSERT_UNREACHABLE("sorry!");
 	return NS_ERROR_NOT_IMPLEMENTED;
 }
 
 
 
 NS_IMETHODIMP
 nsSubscribeDataSource::AddObserver(nsIRDFObserver *n)
 {

--- a/mailnews/base/util/nsMsgIncomingServer.cpp
+++ b/mailnews/base/util/nsMsgIncomingServer.cpp
@@ -956,24 +956,24 @@ nsMsgIncomingServer::SetLocalPath(nsIFil
     rv = NS_OK;
   NS_ENSURE_SUCCESS(rv, rv);
   return SetFileValue("directory-rel", "directory", aLocalPath);
 }
 
 NS_IMETHODIMP
 nsMsgIncomingServer::GetLocalStoreType(nsACString& aResult)
 {
-  NS_NOTYETIMPLEMENTED("nsMsgIncomingServer superclass not implementing GetLocalStoreType!");
+  MOZ_ASSERT_UNREACHABLE("nsMsgIncomingServer superclass not implementing GetLocalStoreType!");
   return NS_ERROR_UNEXPECTED;
 }
 
 NS_IMETHODIMP
 nsMsgIncomingServer::GetLocalDatabaseType(nsACString& aResult)
 {
-  NS_NOTYETIMPLEMENTED("nsMsgIncomingServer superclass not implementing GetLocalDatabaseType!");
+  MOZ_ASSERT_UNREACHABLE("nsMsgIncomingServer superclass not implementing GetLocalDatabaseType!");
   return NS_ERROR_UNEXPECTED;
 }
 
 NS_IMETHODIMP
 nsMsgIncomingServer::GetAccountManagerChrome(nsAString& aResult)
 {
   aResult.AssignLiteral("am-main.xul");
   return NS_OK;