--- a/calendar/lightning/Makefile.in
+++ b/calendar/lightning/Makefile.in
@@ -53,21 +53,19 @@ XPI_PKGNAME = lightning
 XPI_EM_ID = {e2fda1a4-762b-4020-b5ad-a41df1933103}
 
 STRIP_XPI = 1
 DIST_FILES = install.rdf application.ini
 PREF_JS_EXPORTS = $(srcdir)/content/lightning.js
 
 # Lighting version number
 LIGHTNING_VERSION := $(shell cat $(srcdir)/../sunbird/config/version.txt)
-ifdef MOZILLA_2_0_BRANCH
-THUNDERBIRD_VERSION := $(shell cat $(topsrcdir)/mail/config/version-20.txt)
-SEAMONKEY_VERSION := $(shell cat $(topsrcdir)/suite/config/version-20.txt)
-elif defined(MOZILLA_5_0_BRANCH)
+if defined(MOZILLA_5_0_BRANCH)
 THUNDERBIRD_VERSION := $(shell cat $(topsrcdir)/mail/config/version-50.txt)
+SEAMONKEY_VERSION := $(shell cat $(topsrcdir)/suite/config/version-50.txt)
 else
 THUNDERBIRD_VERSION := $(shell cat $(topsrcdir)/mail/config/version.txt)
 SEAMONKEY_VERSION := $(shell cat $(topsrcdir)/suite/config/version.txt)
 endif
 
 ifneq (,$(findstring pre,$(LIGHTNING_VERSION)))
 DEFINES += -DLIGHTNING_PRERELEASE_VERSION=1
 endif

--- a/calendar/providers/gdata/Makefile.in
+++ b/calendar/providers/gdata/Makefile.in
@@ -45,21 +45,19 @@ MODULE = gdata-provider
 
 export USE_EXTENSION_MANIFEST = 1
 export XPI_NAME = gdata-provider
 DIST_FILES = install.rdf
 XPI_PKGNAME = gdata-provider
 STRIP_XPI = 1
 
 CALENDAR_VERSION := $(shell cat $(topsrcdir)/calendar/sunbird/config/version.txt)
-ifdef MOZILLA_2_0_BRANCH
-THUNDERBIRD_VERSION := $(shell cat $(topsrcdir)/mail/config/version-20.txt)
-SEAMONKEY_VERSION := $(shell cat $(topsrcdir)/suite/config/version-20.txt)
-elif defined(MOZILLA_5_0_BRANCH)
+if defined(MOZILLA_5_0_BRANCH)
 THUNDERBIRD_VERSION := $(shell cat $(topsrcdir)/mail/config/version-50.txt)
+SEAMONKEY_VERSION := $(shell cat $(topsrcdir)/suite/config/version-50.txt)
 else
 THUNDERBIRD_VERSION := $(shell cat $(topsrcdir)/mail/config/version.txt)
 SEAMONKEY_VERSION := $(shell cat $(topsrcdir)/suite/config/version.txt)
 endif
 DEFINES += -DAB_CD=$(AB_CD) \
            -DCALENDAR_VERSION=$(CALENDAR_VERSION) \
            -DSEAMONKEY_VERSION=$(SEAMONKEY_VERSION) \
            -DTHUNDERBIRD_VERSION=$(THUNDERBIRD_VERSION) \

--- a/calendar/timezones/Makefile.in
+++ b/calendar/timezones/Makefile.in
@@ -72,21 +72,19 @@ PREF_JS_EXPORTS = $(srcdir)/defaults/pre
 DIRS = locales
 
 ifndef DISABLE_LIGHTNING_INSTALL
 # install as a global extension in dist/bin/extensions/
 INSTALL_EXTENSION_ID = calendar-timezones@mozilla.org
 endif
 
 CALENDAR_VERSION := $(shell cat $(topsrcdir)/calendar/sunbird/config/version.txt)
-ifdef MOZILLA_2_0_BRANCH
-THUNDERBIRD_VERSION := $(shell cat $(topsrcdir)/mail/config/version-20.txt)
-SEAMONKEY_VERSION := $(shell cat $(topsrcdir)/suite/config/version-20.txt)
-elif defined(MOZILLA_5_0_BRANCH)
+if defined(MOZILLA_5_0_BRANCH)
 THUNDERBIRD_VERSION := $(shell cat $(topsrcdir)/mail/config/version-50.txt)
+SEAMONKEY_VERSION := $(shell cat $(topsrcdir)/suite/config/version-50.txt)
 else
 THUNDERBIRD_VERSION := $(shell cat $(topsrcdir)/mail/config/version.txt)
 SEAMONKEY_VERSION := $(shell cat $(topsrcdir)/suite/config/version.txt)
 endif
 TIMEZONES_VERSION := $(shell cat $(srcdir)/config/version.txt)
 
 DEFINES += -DAB_CD=$(AB_CD) \
            -DTHUNDERBIRD_VERSION=$(THUNDERBIRD_VERSION) \

--- a/config/autoconf.mk.in
+++ b/config/autoconf.mk.in
@@ -39,17 +39,16 @@
 # A netscape style .mk file for autoconf builds
 
 INCLUDED_AUTOCONF_MK = 1
 USE_AUTOCONF 	= 1
 MOZILLA_CLIENT	= 1
 COMM_BUILD = @COMM_BUILD@
 MOZILLA_SRCDIR = $(topsrcdir)/mozilla
 MOZILLA_VERSION = @MOZILLA_VERSION@
-MOZILLA_2_0_BRANCH = @MOZILLA_2_0_BRANCH@
 MOZILLA_5_0_BRANCH = @MOZILLA_5_0_BRANCH@
 
 THUNDERBIRD_VERSION	= @THUNDERBIRD_VERSION@
 SUNBIRD_VERSION = @SUNBIRD_VERSION@
 SEAMONKEY_VERSION	= @SEAMONKEY_VERSION@
 
 MOZ_BUILD_APP = @MOZ_BUILD_APP@
 MOZ_APP_NAME	= @MOZ_APP_NAME@

--- a/config/config.mk
+++ b/config/config.mk
@@ -420,26 +420,26 @@ MY_RULES	:= $(DEPTH)/config/myrules.mk
 # Default command macros; can be overridden in <arch>.mk.
 #
 CCC		= $(CXX)
 NFSPWD		= $(CONFIG_TOOLS)/nfspwd
 PURIFY		= purify $(PURIFYOPTIONS)
 QUANTIFY	= quantify $(QUANTIFYOPTIONS)
 ifdef CROSS_COMPILE
 XPIDL_COMPILE 	= $(CYGWIN_WRAPPER) $(LIBXUL_DIST)/host/bin/host_xpidl$(HOST_BIN_SUFFIX)
-ifneq (,$(MOZILLA_2_0_BRANCH)$(MOZILLA_5_0_BRANCH))
+ifdef MOZILLA_5_0_BRANCH
 XPIDL_LINK	= $(CYGWIN_WRAPPER) $(LIBXUL_DIST)/host/bin/host_xpt_link$(HOST_BIN_SUFFIX)
 endif
 else
 XPIDL_COMPILE 	= $(CYGWIN_WRAPPER) $(LIBXUL_DIST)/bin/xpidl$(BIN_SUFFIX)
-ifneq (,$(MOZILLA_2_0_BRANCH)$(MOZILLA_5_0_BRANCH))
+ifdef MOZILLA_5_0_BRANCH
 XPIDL_LINK	= $(CYGWIN_WRAPPER) $(LIBXUL_DIST)/bin/xpt_link$(BIN_SUFFIX)
 endif
 endif
-ifeq (,$(MOZILLA_2_0_BRANCH)$(MOZILLA_5_0_BRANCH))
+ifndef MOZILLA_5_0_BRANCH
 XPIDL_LINK = $(PYTHON) $(SDK_BIN_DIR)/xpt.py link
 endif
 
 INCLUDES = \
   $(LOCAL_INCLUDES) \
   -I$(srcdir) \
   -I. \
   -I$(DIST)/include -I$(DIST)/include/nsprpub \

--- a/config/rules.mk
+++ b/config/rules.mk
@@ -1685,23 +1685,23 @@ ifndef NO_GEN_XPT
 # generate intermediate .xpt files into $(XPIDL_GEN_DIR), then link
 # into $(XPIDL_MODULE).xpt and export it to $(FINAL_TARGET)/components.
 $(XPIDL_GEN_DIR)/%.xpt: %.idl $(XPIDL_COMPILE) $(XPIDL_GEN_DIR)/.done
 	$(REPORT_BUILD)
 	$(ELOG) $(XPIDL_COMPILE) -m typelib -w $(XPIDL_FLAGS) -e $@ -d $(MDDEPDIR)/$*.pp $(_VPATH_SRCS)
 
 # no need to link together if XPIDLSRCS contains only XPIDL_MODULE
 ifneq ($(XPIDL_MODULE).idl,$(strip $(XPIDLSRCS)))
-ifneq (,$(MOZILLA_2_0_BRANCH)$(MOZILLA_5_0_BRANCH))
+ifdef MOZILLA_5_0_BRANCH
 $(XPIDL_GEN_DIR)/$(XPIDL_MODULE).xpt: $(patsubst %.idl,$(XPIDL_GEN_DIR)/%.xpt,$(XPIDLSRCS)) $(GLOBAL_DEPS) $(XPIDL_LINK)
 	$(XPIDL_LINK) $(XPIDL_GEN_DIR)/$(XPIDL_MODULE).xpt $(patsubst %.idl,$(XPIDL_GEN_DIR)/%.xpt,$(XPIDLSRCS))
 else
 $(XPIDL_GEN_DIR)/$(XPIDL_MODULE).xpt: $(patsubst %.idl,$(XPIDL_GEN_DIR)/%.xpt,$(XPIDLSRCS)) $(GLOBAL_DEPS)
 	$(XPIDL_LINK) $(XPIDL_GEN_DIR)/$(XPIDL_MODULE).xpt $(patsubst %.idl,$(XPIDL_GEN_DIR)/%.xpt,$(XPIDLSRCS))
-endif # MOZILLA_2_0_BRANCH || MOZILLA_5_0_BRANCH
+endif # MOZILLA_5_0_BRANCH
 endif # XPIDL_MODULE.xpt != XPIDLSRCS
 
 libs:: $(XPIDL_GEN_DIR)/$(XPIDL_MODULE).xpt
 ifndef NO_DIST_INSTALL
 	$(INSTALL) $(IFLAGS1) $(XPIDL_GEN_DIR)/$(XPIDL_MODULE).xpt $(FINAL_TARGET)/components
 ifndef NO_INTERFACES_MANIFEST
 	@$(PYTHON) $(MOZILLA_DIR)/config/buildlist.py $(FINAL_TARGET)/components/interfaces.manifest "interfaces $(XPIDL_MODULE).xpt"
 	@$(PYTHON) $(MOZILLA_DIR)/config/buildlist.py $(FINAL_TARGET)/chrome.manifest "manifest components/interfaces.manifest"

--- a/configure.in
+++ b/configure.in
@@ -250,26 +250,21 @@ fi
 dnl Get mozilla version from central milestone file
 MOZILLA_VERSION=`$PERL $MOZILLA_SRCDIR/config/milestone.pl -topsrcdir $MOZILLA_SRCDIR`
 
 changequote(,)
 MOZILLA_BRANCH_VERSION=`echo ${MOZILLA_VERSION} | sed -e 's/^\([0-9]\.[0-9]\).*/\1/;'`
 changequote([,])
 
 dnl Set the Gecko branch version.
-MOZILLA_2_0_BRANCH=
 MOZILLA_5_0_BRANCH=
-if test "$MOZILLA_BRANCH_VERSION" = "2.0"; then
-    MOZILLA_2_0_BRANCH=1
-    AC_DEFINE(MOZILLA_2_0_BRANCH)
-elif test "$MOZILLA_BRANCH_VERSION" = "5.0"; then
+if test "$MOZILLA_BRANCH_VERSION" = "5.0"; then
     MOZILLA_5_0_BRANCH=1
     AC_DEFINE(MOZILLA_5_0_BRANCH)
 fi
-AC_SUBST(MOZILLA_2_0_BRANCH)
 AC_SUBST(MOZILLA_5_0_BRANCH)
 
 
 dnl ========================================================
 dnl Checks for compilers.
 dnl ========================================================
 dnl Set CROSS_COMPILE in the environment when running configure
 dnl to use the cross-compile setup for now

--- a/mailnews/import/eudora/src/nsEudoraEditor.cpp
+++ b/mailnews/import/eudora/src/nsEudoraEditor.cpp
@@ -96,23 +96,18 @@ nsEudoraEditor::~nsEudoraEditor()
 
 // readonly attribute nsISelection selection
 NS_IMETHODIMP nsEudoraEditor::GetSelection(nsISelection * *aSelection)
 {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
 
-#ifdef MOZILLA_2_0_BRANCH
-// [noscript] void init (in nsIDOMDocument doc, in nsIPresShellPtr shell, in nsIContentPtr aRoot, in nsISelectionController aSelCon, in unsigned long aFlags)
-NS_IMETHODIMP nsEudoraEditor::Init(nsIDOMDocument *doc, nsIPresShell * shell, nsIContent * aRoot, nsISelectionController *aSelCon, PRUint32 aFlags)
-#else
 // [noscript] void init (in nsIDOMDocument doc, in nsIContentPtr aRoot, in nsISelectionController aSelCon, in unsigned long aFlags)
 NS_IMETHODIMP nsEudoraEditor::Init(nsIDOMDocument *doc, nsIContent * aRoot, nsISelectionController *aSelCon, PRUint32 aFlags)
-#endif
 {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
 
 // void setAttributeOrEquivalent (in nsIDOMElement element, in AString sourceAttrName, in AString sourceAttrValue, in boolean aSuppressTransaction)
 NS_IMETHODIMP nsEudoraEditor::SetAttributeOrEquivalent(nsIDOMElement *element, const nsAString & sourceAttrName, const nsAString & sourceAttrValue, PRBool aSuppressTransaction)
 {
@@ -620,23 +615,21 @@ NS_IMETHODIMP nsEudoraEditor::DebugDumpC
 
 
 // void debugUnitTests (out long outNumTests, out long outNumTestsFailed)
 NS_IMETHODIMP nsEudoraEditor::DebugUnitTests(PRInt32 *outNumTests, PRInt32 *outNumTestsFailed)
 {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
-#ifndef MOZILLA_2_0_BRANCH
 //  readonly attribute boolean transactionManager
 NS_IMETHODIMP nsEudoraEditor::GetLastKeypressEventTrusted(PRBool *aResult)
 {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
-#endif
 
 // void pasteAsQuotation (in long aSelectionType)
 NS_IMETHODIMP nsEudoraEditor::PasteAsQuotation(PRInt32 aSelectionType)
 {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
 
@@ -1070,23 +1063,16 @@ NS_IMETHODIMP nsEudoraHTMLImageElement::
 
 
 // attribute DOMString prefix
 NS_IMETHODIMP nsEudoraHTMLImageElement::GetPrefix(nsAString & aPrefix)
 {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
-#ifdef MOZILLA_2_0_BRANCH
-NS_IMETHODIMP nsEudoraHTMLImageElement::SetPrefix(const nsAString & aPrefix)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-#endif
-
 // readonly attribute DOMString localName
 NS_IMETHODIMP nsEudoraHTMLImageElement::GetLocalName(nsAString & aLocalName)
 {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
 
 // boolean hasAttributes ()
@@ -1267,17 +1253,16 @@ NS_IMETHODIMP nsEudoraHTMLImageElement::
 }
 
 
 NS_IMETHODIMP nsEudoraHTMLImageElement::SetClassName(const nsAString & aClassName)
 {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
-#ifndef MOZILLA_2_0_BRANCH
 NS_IMETHODIMP nsEudoraHTMLImageElement::GetAccessKey(nsAString &aAccessKey)
 {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
 NS_IMETHODIMP nsEudoraHTMLImageElement::SetAccessKey(const nsAString &aAccessKey)
 {
   return NS_ERROR_NOT_IMPLEMENTED;
@@ -1292,17 +1277,16 @@ NS_IMETHODIMP nsEudoraHTMLImageElement::
 {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
 NS_IMETHODIMP nsEudoraHTMLImageElement::Click()
 {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
-#endif
 
 // attribute DOMString name
 NS_IMETHODIMP nsEudoraHTMLImageElement::GetName(nsAString & aName)
 {
   return NS_OK;
 }
 
 

deleted file mode 100644
--- a/suite/config/version-20.txt
+++ /dev/null
@@ -1,1 +0,0 @@
-2.1pre
\ No newline at end of file

copy from suite/config/version.txt
copy to suite/config/version-50.txt

--- a/suite/confvars.sh
+++ b/suite/confvars.sh
@@ -54,19 +54,19 @@ MOZ_HELP_VIEWER=1
 MOZ_MORK=1
 MOZ_STATIC_BUILD_UNSUPPORTED=1
 MOZ_APP_COMPONENT_LIBS="xpautocomplete $MAIL_COMPONENT $LDAP_COMPONENT"
 MOZ_APP_COMPONENT_MODULES="MODULE(xpAutoComplete) $MAIL_MODULE $LDAP_MODULE"
 MOZ_APP_EXTRA_LIBS="$LDAP_LIBS"
 MOZ_SERVICES_SYNC=1
 
 # Needed for the mozilla-central build side of the system.
-# Can be dropped when we branch MOZILLA_2_0_BRANCH
+# Can be dropped when we branch MOZILLA_5_0_BRANCH
 MOZILLA_BRANCH_VERSION=`echo ${MOZILLA_VERSION} | sed -e 's/^\([0-9]\.[0-9]\).*/\1/;'`
 
-if test "$MOZILLA_BRANCH_VERSION" = "2.0"; then
-  MOZ_APP_VERSION_TXT=${_topsrcdir}/$MOZ_BUILD_APP/config/version-20.txt
+if test "$MOZILLA_BRANCH_VERSION" = "5.0"; then
+  MOZ_APP_VERSION_TXT=${_topsrcdir}/$MOZ_BUILD_APP/config/version-50.txt
 else
   MOZ_APP_VERSION_TXT=${_topsrcdir}/$MOZ_BUILD_APP/config/version.txt
 fi
 
 MOZ_APP_VERSION=`cat $MOZ_APP_VERSION_TXT`
 SEAMONKEY_VERSION=$MOZ_APP_VERSION