new file mode 100644
--- /dev/null
+++ b/mail/defs.mk
@@ -0,0 +1,8 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# The variables defined here will be set for all files within the mail/
+# subdirectory.
+
+XPI_ROOT_APPID=$(MOZ_APP_ID)

--- a/mail/locales/Makefile.in
+++ b/mail/locales/Makefile.in
@@ -58,33 +58,37 @@ SEARCHPLUGINS := $(foreach plugin,$(adds
 SEARCHPLUGINS_FLAGS := --silence-missing-directive-warnings
 PP_TARGETS += SEARCHPLUGINS
 
 list-json = $(SEARCHPLUGINS_PATH)/list.json
 GARBAGE += $(list-json)
 
 libs:: searchplugins
 
+# Required for l10n.mk - defines a list of app sub dirs that should
+# be included in langpack xpis.
+DIST_SUBDIRS = $(DIST_SUBDIR)
+
 include $(topsrcdir)/config/rules.mk
 
 include $(topsrcdir)/mozilla/toolkit/locales/l10n.mk
 
 $(list-json): $(call mkdir_deps,$(SEARCHPLUGINS_PATH)) $(if $(IS_LANGUAGE_REPACK),FORCE)
 	$(shell $(PYTHON) $(srcdir)/searchjson.py $(srcdir)/search/list.json $(AB_CD) $(list-json))
 searchplugins:: $(list-json)
 
 $(STAGEDIST): $(DIST)/branding
 
 $(DIST)/branding:
 	$(NSINSTALL) -D $@
 
 libs-%:
 	$(NSINSTALL) -D $(DIST)/install
-	@$(MAKE) -C $(DEPTH)/toolkit/locales libs-$*
-	@$(MAKE) -C $(DEPTH)/devtools/client/locales AB_CD=$* XPI_NAME=locale-$*
+	@$(MAKE) -C $(DEPTH)/toolkit/locales libs-$*  XPI_ROOT_APPID='$(XPI_ROOT_APPID)'
+	@$(MAKE) -C $(DEPTH)/devtools/client/locales AB_CD=$* XPI_NAME=locale-$* XPI_ROOT_APPID='$(XPI_ROOT_APPID)'
 	@$(MAKE) -C ../../chat/locales AB_CD=$* XPI_NAME=locale-$*
 	@$(MAKE) -C ../../editor/ui/locales AB_CD=$* XPI_NAME=locale-$*
 	@$(MAKE) -C $(DEPTH)/extensions/spellcheck/locales AB_CD=$* XPI_NAME=locale-$*
 	@$(MAKE) -C $(DEPTH)/intl/locales AB_CD=$* XPI_NAME=locale-$*
 	@$(MAKE) -B searchplugins AB_CD=$* XPI_NAME=locale-$*
 	@$(MAKE) libs AB_CD=$* XPI_NAME=locale-$* PREF_DIR=defaults/pref
 	@$(MAKE) -C $(DEPTH)/$(MOZ_BRANDING_DIRECTORY)/locales AB_CD=$* XPI_NAME=locale-$*