--- a/mail/config/mozconfigs/macosx64/l10n-mozconfig
+++ b/mail/config/mozconfigs/macosx64/l10n-mozconfig
@@ -4,17 +4,16 @@ ac_add_options --enable-application=mail
 ac_add_options --enable-update-channel=${MOZ_UPDATE_CHANNEL}
 ac_add_options --disable-install-strip
 ac_add_options --enable-profiling
 ac_add_options --with-l10n-base=../../l10n
 ac_add_options --disable-compile-environment
 
 # Build lightning locales
 ac_add_options --enable-calendar
-mk_add_options MOZ_POSTFLIGHT_ALL+=calendar/lightning/build/universal.mk
 
 # Disable checking that add-ons are signed by the trusted root
 MOZ_ADDON_SIGNING=0
 # Disable enforcing that add-ons are signed by the trusted root
 MOZ_REQUIRE_ADDON_SIGNING=0
 
 # Run client.py
 mk_add_options CLIENT_PY_ARGS="$([ -f $topsrcdir/build/client.py-l10n-args ] && cat $topsrcdir/build/client.py-l10n-args)"

copy from mail/config/mozconfigs/macosx-universal/nightly
copy to mail/config/mozconfigs/macosx64/nightly
--- a/mail/config/mozconfigs/macosx-universal/nightly
+++ b/mail/config/mozconfigs/macosx64/nightly
@@ -2,23 +2,18 @@
 # mixed up with host/target CPUs when trying to work out how to do the
 # universal build. When we redo the build system (bug 648979) this will
 # go away.
 if test -e "$topsrcdir/mail/config/version.txt"; then
   unset CC
   unset CXX
 fi
 
-# Make sure Lightning is also unified, this needs to happen before including
-# the universal mozconfig because Lightning's univeral.mk needs to run first.
-mk_add_options MOZ_POSTFLIGHT_ALL+=calendar/lightning/build/universal.mk
+. $topsrcdir/build/macosx/mozconfig.common
 
-. $topsrcdir/build/macosx/universal/mozconfig
-
-# Universal builds override the default of mail (bug 575283 comment 29)
 ac_add_options --enable-application=mail
 ac_add_options --enable-update-channel=${MOZ_UPDATE_CHANNEL}
 ac_add_options --disable-install-strip
 ac_add_options --enable-profiling
 ac_add_options --enable-calendar
 
 # For NSS symbols
 export MOZ_DEBUG_SYMBOLS=1

copy from mail/config/mozconfigs/macosx-universal/release
copy to mail/config/mozconfigs/macosx64/release
--- a/mail/config/mozconfigs/macosx-universal/release
+++ b/mail/config/mozconfigs/macosx64/release
@@ -2,23 +2,18 @@
 # mixed up with host/target CPUs when trying to work out how to do the
 # universal build. When we redo the build system (bug 648979) this will
 # go away.
 if test -e "$topsrcdir/mail/config/version.txt"; then
   unset CC
   unset CXX
 fi
 
-# Make sure Lightning is also unified, this needs to happen before including
-# the universal mozconfig because Lightning's univeral.mk needs to run first.
-mk_add_options MOZ_POSTFLIGHT_ALL+=calendar/lightning/build/universal.mk
+. $topsrcdir/build/macosx/mozconfig.common
 
-. $topsrcdir/build/macosx/universal/mozconfig
-
-# Universal builds override the default of mail (bug 575283 comment 29)
 ac_add_options --enable-application=mail
 ac_add_options --enable-update-channel=${MOZ_UPDATE_CHANNEL}
 ac_add_options --enable-official-branding
 ac_add_options --enable-calendar
 
 # For NSS symbols
 export MOZ_DEBUG_SYMBOLS=1