--- a/mail/Makefile.in
+++ b/mail/Makefile.in
@@ -37,22 +37,16 @@
 
 DEPTH		= ..
 topsrcdir	= @top_srcdir@
 srcdir		= @srcdir@
 VPATH		= @srcdir@
 
 include $(topsrcdir)/config/config.mk
 
-# For non-libxul builds this gets linked into its own library. For libxul
-# builds, the build of components is controlled in mail/build.mk
-ifndef MOZ_ENABLE_LIBXUL
-DIRS += components
-endif
-
 # app is always last as it packages up the built files on mac
 DIRS += base locales extensions steel themes jquery app
 
 ifeq ($(OS_ARCH),WINNT)
 ifdef MOZ_INSTALLER
 # though some lasts are more last than others
 DIRS += installer/windows
 endif

--- a/mail/app/Makefile.in
+++ b/mail/app/Makefile.in
@@ -112,22 +112,17 @@ endif
 
 ifeq (cocoa,$(MOZ_WIDGET_TOOLKIT))
 TK_LIBS := -framework Cocoa $(TK_LIBS)
 ifdef BUILD_STATIC_LIBS
 TK_LIBS := -framework SystemConfiguration $(TK_LIBS)
 endif
 endif
 
-ifdef MOZ_ENABLE_LIBXUL
 APP_XPCOM_LIBS = $(XPCOM_GLUE_LDOPTS)
-else
-MOZILLA_INTERNAL_API = 1
-APP_XPCOM_LIBS = $(XPCOM_LIBS)
-endif
 
 LIBS += \
 	$(STATIC_COMPONENTS_LINKER_PATH) \
 	$(EXTRA_DSO_LIBS) \
 	$(APP_XPCOM_LIBS) \
 	$(NSPR_LIBS) \
 	$(NULL)
 
@@ -146,22 +141,16 @@ endif
 ifdef MOZ_JPROF
 LIBS += -ljprof
 endif
 
 ifdef MOZ_ENABLE_DBUS
 LIBS += $(MOZ_DBUS_GLIB_LIBS)
 endif
 
-ifndef MOZ_ENABLE_LIBXUL
-ifdef MOZ_NATIVE_HUNSPELL
-LIBS += $(MOZ_HUNSPELL_LIBS)
-endif
-endif
-
 ifndef MOZ_WINCONSOLE
 ifdef MOZ_DEBUG
 MOZ_WINCONSOLE = 1
 else
 MOZ_WINCONSOLE = 0
 endif
 endif
 

--- a/mail/build.mk
+++ b/mail/build.mk
@@ -32,43 +32,34 @@
 # and other provisions required by the GPL or the LGPL. If you do not delete
 # the provisions above, a recipient may use your version of this file under
 # the terms of any one of the MPL, the GPL or the LGPL.
 #
 # ***** END LICENSE BLOCK *****
 
 ifndef COMM_BUILD # Mozilla Makefile
 
-ifdef MOZ_ENABLE_LIBXUL
 SUBDIR=/..
 include $(topsrcdir)/../bridge/bridge.mk
 # For libxul builds this gets linked into libxul. For non-libxul
 # builds, the build of components is controlled in mail/Makefile.in
 APP_LIBXUL_DIRS += $(DEPTH)/../mail/components
-endif
 
 ifndef LIBXUL_SDK
 include $(topsrcdir)/toolkit/toolkit-tiers.mk
 endif
 
 TIERS += app
 
 ifdef MOZ_EXTENSIONS
 tier_app_dirs += extensions
 endif
 
 else # toplevel Makefile
 
-ifndef MOZ_ENABLE_LIBXUL
-SUBDIR =
-include $(topsrcdir)/bridge/bridge.mk
-tier_app_staticdirs += $(APP_LIBXUL_STATICDIRS)
-tier_app_dirs += $(APP_LIBXUL_DIRS)
-endif
-
 TIERS += app
 
 ifdef MOZ_COMPOSER
 tier_app_dirs += editor/ui
 endif
 
 tier_app_dirs += $(MOZ_BRANDING_DIRECTORY)
 

--- a/mail/components/build/Makefile.in
+++ b/mail/components/build/Makefile.in
@@ -43,29 +43,19 @@ VPATH		= @srcdir@
 include $(DEPTH)/config/autoconf.mk
 
 MODULE		= mailcomps
 LIBRARY_NAME	= mailcomps
 SHORT_LIBNAME	= mailcmp
 EXPORT_LIBRARY	= 1
 IS_COMPONENT	= 1
 MODULE_NAME	= nsMailCompsModule
-ifdef MOZ_ENABLE_LIBXUL
 LIBXUL_LIBRARY = 1
 MOZILLA_INTERNAL_API = 1
 FORCE_USE_PIC = 1
-else
-ifdef BUILD_STATIC_LIBS
-MOZILLA_INTERNAL_API = 1
-else
-ifneq ($(MOZ_WIDGET_TOOLKIT), gtk2)
-MOZILLA_INTERNAL_API = 1
-endif
-endif
-endif
 
 CPPSRCS = nsMailComps.cpp \
           $(NULL)
 
 ifeq ($(OS_ARCH),WINNT)
 OS_LIBS += $(call EXPAND_LIBNAME,ole32 shell32)
 endif
 

--- a/mail/components/migration/src/Makefile.in
+++ b/mail/components/migration/src/Makefile.in
@@ -3,23 +3,17 @@ topsrcdir=@top_srcdir@
 srcdir=@srcdir@
 VPATH=@srcdir@
 
 include $(DEPTH)/config/autoconf.mk
 
 MODULE=mailprofilemigration
 LIBRARY_NAME = profilemigration_s
 MODULE_NAME = nsMailProfileMigratorModule
-# Linux builds should use external API except when we are building libxul.
-ifneq ($(MOZ_WIDGET_TOOLKIT), gtk2)
 MOZILLA_INTERNAL_API = 1
-endif
-ifdef MOZ_ENABLE_LIBXUL
-MOZILLA_INTERNAL_API = 1
-endif
 
 CPPSRCS = \
 	nsProfileMigrator.cpp \
 	nsMailProfileMigratorUtils.cpp \
 	nsNetscapeProfileMigratorBase.cpp \
 	nsSeamonkeyProfileMigrator.cpp \
 	$(NULL)
 

--- a/mail/components/shell/Makefile.in
+++ b/mail/components/shell/Makefile.in
@@ -44,23 +44,17 @@ include $(DEPTH)/config/autoconf.mk
 
 DIRS = public
 
 DEFINES += -DMOZ_APP_NAME=\"$(MOZ_APP_NAME)\"
 
 MODULE = shellservice
 LIBRARY_NAME = shellservice_s
 MODULE_NAME = nsMailShellModule
-# Linux builds should use external API except when we are building libxul.
-ifneq ($(MOZ_WIDGET_TOOLKIT), gtk2)
 MOZILLA_INTERNAL_API = 1
-endif
-ifdef MOZ_ENABLE_LIBXUL
-MOZILLA_INTERNAL_API = 1
-endif
 
 EXTRA_COMPONENTS = \
   nsSetDefaultMail.js \
   shell.manifest \
   $(NULL)
 
 ifeq ($(OS_ARCH),WINNT)
 CPPSRCS = nsMailWinIntegration.cpp

--- a/mail/installer/Makefile.in
+++ b/mail/installer/Makefile.in
@@ -100,20 +100,16 @@ endif
 
 ifeq (cocoa,$(MOZ_WIDGET_TOOLKIT))
 MOZ_PKG_MAC_DSSTORE=branding/dsstore
 MOZ_PKG_MAC_BACKGROUND=branding/background.png
 MOZ_PKG_MAC_ICON=branding/disk.icns
 MOZ_PKG_MAC_EXTRA=--symlink "/Applications:/ "
 endif
 
-ifndef MOZ_ENABLE_LIBXUL
-$(error you need an "--enable-libxul" build to package a build)
-endif
-
 NON_OMNIJAR_FILES = defaults/messenger/mailViews.dat
 
 ifndef LIBXUL_SDK
 INSTALL_SDK = 1
 endif
 
 include $(MOZILLA_SRCDIR)/toolkit/mozapps/installer/packager.mk
 

--- a/mailnews/base/public/msgCore.h
+++ b/mailnews/base/public/msgCore.h
@@ -201,25 +201,13 @@ NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODUL
 #if defined(XP_WIN) || defined(XP_OS2)
 #define MSG_LINEBREAK "\015\012"
 #define MSG_LINEBREAK_LEN 2
 #else
 #define MSG_LINEBREAK "\012"
 #define MSG_LINEBREAK_LEN 1
 #endif
 
-#if defined(MOZ_ENABLE_LIBXUL)
 #define NS_MSG_BASE
 #define NS_MSG_BASE_STATIC_MEMBER_(type) type
-#else
-
-#ifdef _IMPL_NS_MSG_BASE
-#define NS_MSG_BASE                      NS_EXPORT
-#define NS_MSG_BASE_STATIC_MEMBER_(type) NS_EXPORT_STATIC_MEMBER_(type)
-#else
-#define NS_MSG_BASE                      NS_IMPORT
-#define NS_MSG_BASE_STATIC_MEMBER_(type) NS_IMPORT_STATIC_MEMBER_(type)
-#endif
-
-#endif // MOZ_ENABLE_LIBXUL
 
 #endif // msgCore_h__
 

--- a/mailnews/base/test/Makefile.in
+++ b/mailnews/base/test/Makefile.in
@@ -40,27 +40,16 @@
 DEPTH		= ../../..
 topsrcdir	= @top_srcdir@
 srcdir		= @srcdir@
 VPATH		= @srcdir@
 relativesrcdir = mailnews/base/test
 
 include $(DEPTH)/config/autoconf.mk
 
-ifndef MOZ_ENABLE_LIBXUL
-ifndef MOZ_INCOMPLETE_EXTERNAL_LINKAGE
-MOZILLA_INTERNAL_API = 1
-endif
-
-# XXX This needs functions exporting in the libxul case.
-CPP_UNIT_TESTS = \
-    TestMsgStripRE.cpp \
-    $(NULL)
-endif
-
 include $(topsrcdir)/config/config.mk
 
 XPCSHELL_TESTS = unit
 
 include $(topsrcdir)/config/rules.mk
 
 LOCAL_INCLUDES = \
     -I$(MOZILLA_SRCDIR)/xpcom/tests \

--- a/mailnews/imap/test/Makefile.in
+++ b/mailnews/imap/test/Makefile.in
@@ -40,28 +40,16 @@
 DEPTH		= ../../..
 topsrcdir	= @top_srcdir@
 srcdir		= @srcdir@
 VPATH		= @srcdir@
 relativesrcdir = mailnews/imap/test
 
 include $(DEPTH)/config/autoconf.mk
 
-ifndef MOZ_ENABLE_LIBXUL
-ifndef MOZ_INCOMPLETE_EXTERNAL_LINKAGE
-MOZILLA_INTERNAL_API = 1
-endif
-
-# XXX This needs functions exporting in the libxul case.
-CPP_UNIT_TESTS = \
-		TestImapHdrXferInfo.cpp \
-		TestImapFlagAndUidState.cpp \
-		$(NULL)
-endif
-
 include $(topsrcdir)/config/config.mk
 
 XPCSHELL_TESTS = unit
 
 include $(topsrcdir)/config/rules.mk
 
 LOCAL_INCLUDES = \
 		-I$(MOZILLA_SRCDIR)/xpcom/tests \

--- a/mailnews/mime/test/Makefile.in
+++ b/mailnews/mime/test/Makefile.in
@@ -39,27 +39,12 @@
 DEPTH		= ../../..
 topsrcdir	= @top_srcdir@
 srcdir		= @srcdir@
 VPATH		= @srcdir@
 relativesrcdir = mailnews/mime/test
 
 include $(DEPTH)/config/autoconf.mk
 
-ifndef MOZ_ENABLE_LIBXUL
-ifndef MOZ_INCOMPLETE_EXTERNAL_LINKAGE
-MOZILLA_INTERNAL_API = 1
-endif
-
-CPP_UNIT_TESTS = \
-		TestMimeCrash.cpp \
-		$(NULL)
-
-LIBS += \
-	$(XPCOM_LIBS) \
-	$(NSPR_LIBS) \
-	$(NULL)
-endif
-
 XPCSHELL_TESTS = unit
 
 include $(topsrcdir)/config/rules.mk
 

--- a/suite/app/Makefile.in
+++ b/suite/app/Makefile.in
@@ -98,22 +98,17 @@ endif
 
 ifeq (cocoa,$(MOZ_WIDGET_TOOLKIT))
 TK_LIBS := -framework Cocoa $(TK_LIBS)
 ifdef BUILD_STATIC_LIBS
 TK_LIBS := -framework SystemConfiguration $(TK_LIBS)
 endif
 endif
 
-ifdef MOZ_ENABLE_LIBXUL
 APP_XPCOM_LIBS = $(XPCOM_GLUE_LDOPTS)
-else
-MOZILLA_INTERNAL_API = 1
-APP_XPCOM_LIBS = $(XPCOM_LIBS)
-endif
 
 LIBS += \
 	$(STATIC_COMPONENTS_LINKER_PATH) \
 	$(EXTRA_DSO_LIBS) \
 	$(APP_XPCOM_LIBS) \
 	$(NSPR_LIBS) \
 	$(NULL)
 
@@ -132,22 +127,16 @@ endif
 ifdef MOZ_JPROF
 LIBS += -ljprof
 endif
 
 ifdef MOZ_ENABLE_DBUS
 LIBS += $(MOZ_DBUS_GLIB_LIBS)
 endif
 
-ifndef MOZ_ENABLE_LIBXUL
-ifdef MOZ_NATIVE_HUNSPELL
-LIBS += $(MOZ_HUNSPELL_LIBS)
-endif
-endif
-
 ifndef MOZ_WINCONSOLE
 ifdef MOZ_DEBUG
 MOZ_WINCONSOLE = 1
 else
 MOZ_WINCONSOLE = 0
 endif
 endif
 

--- a/suite/build.mk
+++ b/suite/build.mk
@@ -32,42 +32,33 @@
 # and other provisions required by the GPL or the LGPL. If you do not delete
 # the provisions above, a recipient may use your version of this file under
 # the terms of any one of the MPL, the GPL or the LGPL.
 #
 # ***** END LICENSE BLOCK *****
 
 ifndef COMM_BUILD # Mozilla Makefile
 
-ifdef MOZ_ENABLE_LIBXUL
 SUBDIR=/..
 include $(topsrcdir)/../bridge/bridge.mk
-endif
 
 ifndef LIBXUL_SDK
 include $(topsrcdir)/toolkit/toolkit-tiers.mk
 endif
 
 TIERS += app
 
 ifdef MOZ_EXTENSIONS
 tier_app_dirs += extensions
 endif
 
 tier_app_dirs += services
 
 else # toplevel Makefile
 
-ifndef MOZ_ENABLE_LIBXUL
-SUBDIR=
-include $(topsrcdir)/bridge/bridge.mk
-tier_app_staticdirs += $(APP_LIBXUL_STATICDIRS)
-tier_app_dirs += $(APP_LIBXUL_DIRS)
-endif
-
 TIERS += app
 
 ifdef MOZ_COMPOSER
 tier_app_dirs += editor/ui
 endif
 
 tier_app_dirs += $(MOZ_BRANDING_DIRECTORY)
 

--- a/suite/installer/Makefile.in
+++ b/suite/installer/Makefile.in
@@ -41,26 +41,17 @@ srcdir		= @srcdir@
 VPATH		= @srcdir@
 
 include $(DEPTH)/config/autoconf.mk
 
 include $(topsrcdir)/config/rules.mk
 
 MOZ_PKG_REMOVALS = $(srcdir)/removed-files.in
 
-ifdef MOZ_ENABLE_LIBXUL
 MOZ_PKG_MANIFEST_P = $(srcdir)/package-manifest.in
-else
-define message
-You need to build with --enable-libxul (the default, unless you specify
---disable-libxul or --enable-shared or --enable-debug) to package a build.
-endef
-default libs installer::
-  $(error $(message))
-endif
 
 MOZ_NONLOCALIZED_PKG_LIST = \
 	xpcom \
 	browser \
 	mail \
 	$(NULL)
 
 MOZ_LOCALIZED_PKG_LIST = \