--- a/mail/locales/en-US/chrome/messenger/charsetTitles.properties
+++ b/mail/locales/en-US/chrome/messenger/charsetTitles.properties
@@ -30,17 +30,16 @@ x-mac-croatian.title    = Croatian (MacC
 x-mac-romanian.title    = Romanian (MacRomanian)
 x-mac-icelandic.title   = Icelandic (MacIcelandic)
 iso-2022-jp.title = Japanese (ISO-2022-JP)
 shift_jis.title = Japanese (Shift_JIS)
 euc-jp.title = Japanese (EUC-JP)
 big5.title = Chinese Traditional (Big5)
 big5-hkscs.title = Chinese Traditional (Big5-HKSCS)
 gb2312.title = Chinese Simplified (GB2312)
-hz-gb-2312.title = Chinese Simplified (HZ)
 gbk.title = Chinese Simplified (GBK)
 euc-kr.title = Korean (EUC-KR)
 utf-7.title = Unicode (UTF-7)
 utf-8.title = Unicode (UTF-8)
 utf-16.title = Unicode (UTF-16)
 utf-16le.title = Unicode (UTF-16LE)
 utf-16be.title = Unicode (UTF-16BE)
 iso-8859-5.title = Cyrillic (ISO-8859-5)

--- a/mailnews/compose/src/nsMsgCompUtils.cpp
+++ b/mailnews/compose/src/nsMsgCompUtils.cpp
@@ -930,18 +930,17 @@ msg_generate_message_id (nsIMsgIdentity 
   return PR_smprintf("<%lX.%lX@%s>",
            (unsigned long) now, (unsigned long) salt, host);
 }
 
 
 inline static bool is7bitCharset(const nsCString& charset)
 {
   // charset name is canonical (no worry about case-sensitivity)
-  return charset.EqualsLiteral("HZ-GB-2312") ||
-         Substring(charset, 0, 8).EqualsLiteral("ISO-2022-");
+  return Substring(charset, 0, 8).EqualsLiteral("ISO-2022-");
 }
 
 #define PR_MAX_FOLDING_LEN 75     // this is to gurantee the folded line will
                                   // never be greater than 78 = 75 + CRLFLWSP
 /*static */ char *
 RFC2231ParmFolding(const char *parmName, const nsCString& charset,
                    const char *language, const nsString& parmValue)
 {

--- a/mailnews/intl/charsetData.properties
+++ b/mailnews/intl/charsetData.properties
@@ -45,17 +45,16 @@ x-x-big5.LangGroup                 = zh-
 big5-hkscs.LangGroup               = zh-HK
 euc-jp.LangGroup                   = ja
 euc-kr.LangGroup                   = ko
 gb2312.LangGroup                   = zh-CN
 gb18030.LangGroup                  = zh-CN
 gb18030.2000-0.LangGroup           = zh-CN
 gb18030.2000-1.LangGroup           = zh-CN
 hkscs-1.LangGroup                  = zh-HK
-hz-gb-2312.LangGroup               = zh-CN
 ibm866.LangGroup                   = x-cyrillic
 ibm1125.LangGroup                  = x-cyrillic
 ibm1131.LangGroup                  = x-cyrillic
 iso-2022-jp.LangGroup              = ja
 iso-8859-1.LangGroup               = x-western
 iso-8859-10.LangGroup              = x-western
 iso-8859-14.LangGroup              = x-western
 iso-8859-15.LangGroup              = x-western
@@ -86,17 +85,16 @@ windows-1251.LangGroup             = x-c
 windows-1252.LangGroup             = x-western
 windows-1253.LangGroup             = el
 windows-1254.LangGroup             = x-western
 windows-1255.LangGroup             = he
 windows-1256.LangGroup             = ar
 windows-1257.LangGroup             = x-western
 windows-1258.LangGroup             = x-western
 gbk.LangGroup                      = zh-CN
-gb_2312-80.LangGroup               = zh-CN
 x-mac-ce.LangGroup                 = x-western
 x-mac-croatian.LangGroup           = x-western
 x-mac-cyrillic.LangGroup           = x-cyrillic
 x-mac-devanagari.LangGroup         = x-devanagari
 x-mac-farsi.LangGroup              = ar
 x-mac-greek.LangGroup              = el
 x-mac-gujarati.LangGroup           = x-gujr
 x-mac-gurmukhi.LangGroup           = x-guru
@@ -111,13 +109,12 @@ x-mac-hebrew.LangGroup             = he
 x-mac-arabic.LangGroup             = ar
 
 iso-2022-jp.isMultibyte     = true
 shift_jis.isMultibyte       = true
 euc-jp.isMultibyte          = true
 big5.isMultibyte            = true
 big5-hkscs.isMultibyte      = true
 gb2312.isMultibyte          = true
-hz-gb-2312.isMultibyte      = true
 euc-kr.isMultibyte          = true
 utf-7.isMultibyte           = true
 utf-8.isMultibyte           = true
 replacement.isMultibyte     = true

--- a/mailnews/intl/charsetalias.properties
+++ b/mailnews/intl/charsetalias.properties
@@ -12,18 +12,16 @@
 # This file contains mainly aliases. Actual labels for encodings are in
 # labelsencodings.properties. Besides aliases it contains labels for charsets
 # that are not part of the HTML5 world, but still are supported for e-mail.
 
 646=windows-1252
 iso-8859-1=ISO-8859-1
 utf-16=UTF-16
 utf-7=UTF-7
-gb2312=GB2312
-hz-gb-2312=HZ-GB-2312
 
 # Netscape private ...
 x-imap4-modified-utf7=x-imap4-modified-utf7
 x-mac-ce=x-mac-ce
 x-mac-turkish=x-mac-turkish
 x-mac-greek=x-mac-greek
 x-mac-icelandic=x-mac-icelandic
 x-mac-croatian=x-mac-croatian
@@ -63,28 +61,16 @@ csiso2022jp2=ISO-2022-JP
 # x-x-big5 is not really a alias for Big5, add it only for MS FrontPage
 # Sun Solaris
 
 zh_tw-big5=Big5
 
 # Aliases for EUC-KR
 5601=EUC-KR
 
-# Aliases for GB2312
-# The following are really not aliases GB2312, add them only for MS FrontPage
-gb_2312-80=GB2312
-iso-ir-58=GB2312
-chinese=GB2312
-csiso58gb231280=GB2312
-csgb2312=GB2312
-zh_cn.euc=GB2312
-
-# Sun Solaris
-gb_2312=GB2312
-
 # Aliases for windows-874 
 tis620=windows-874
 
 # Aliases for IBM866
 cp-866=IBM866
 
 # Aliases for UTF-7
 x-unicode-2-0-utf-7=UTF-7