--- a/mailnews/addrbook/src/nsAbWinHelper.cpp
+++ b/mailnews/addrbook/src/nsAbWinHelper.cpp
@@ -509,17 +509,17 @@ BOOL nsAbWinHelper::DeleteEntry(const ns
 BOOL nsAbWinHelper::SetPropertyUString(const nsMapiEntry& aObject, ULONG aPropertyTag, 
                                        const char16_t *aValue)
 {
     SPropValue value ;
     nsAutoCString alternativeValue ;
 
     value.ulPropTag = aPropertyTag ;
     if (PROP_TYPE(aPropertyTag) == PT_UNICODE) {
-        value.Value.lpszW = wwc(const_cast<char16_t *>(aValue)) ;
+        value.Value.lpszW = reinterpret_cast<wchar_t*>(const_cast<char16_t *>(aValue));
     }
     else if (PROP_TYPE(aPropertyTag) == PT_STRING8) {
         alternativeValue = NS_LossyConvertUTF16toASCII(aValue);
         value.Value.lpszA = const_cast<char *>(alternativeValue.get()) ;
     }
     else {
         PRINTF(("Property %08x is not a string.\n", aPropertyTag)) ;
         return TRUE ;

--- a/mailnews/import/outlook/src/MapiApi.cpp
+++ b/mailnews/import/outlook/src/MapiApi.cpp
@@ -8,25 +8,24 @@
 
 #include <sstream>
 #include "rtfMailDecoder.h"
 
 #include "prprf.h"
 #include "nsMemory.h"
 #include "nsMsgUtils.h"
 #include "nsUnicharUtils.h"
+#include "nsNativeCharsetUtils.h"
 
 int      CMapiApi::m_clients = 0;
 BOOL    CMapiApi::m_initialized = false;
 nsTArray<CMsgStore*>  *CMapiApi::m_pStores = NULL;
 LPMAPISESSION CMapiApi::m_lpSession = NULL;
 LPMDB    CMapiApi::m_lpMdb = NULL;
 HRESULT    CMapiApi::m_lastError;
-char16_t *  CMapiApi::m_pUniBuff = NULL;
-int      CMapiApi::m_uniBuffLen = 0;
 /*
 Type: 1, name: Calendar, class: IPF.Appointment
 Type: 1, name: Contacts, class: IPF.Contact
 Type: 1, name: Journal, class: IPF.Journal
 Type: 1, name: Notes, class: IPF.StickyNote
 Type: 1, name: Tasks, class: IPF.Task
 Type: 1, name: Drafts, class: IPF.Note
 */
@@ -280,38 +279,22 @@ CMapiApi::~CMapiApi()
     }
 
     if (m_initialized) {
       MAPIUninitialize();
       m_initialized = FALSE;
     }
 
     UnloadMapi();
-
-    if (m_pUniBuff)
-      delete [] m_pUniBuff;
-    m_pUniBuff = NULL;
-    m_uniBuffLen = 0;
   }
 }
 
 void CMapiApi::CStrToUnicode(const char *pStr, nsString& result)
 {
-  result.Truncate();
-  int wLen = MultiByteToWideChar(CP_ACP, 0, pStr, -1, wwc(m_pUniBuff), 0);
-  if (wLen >= m_uniBuffLen) {
-    if (m_pUniBuff)
-      delete [] m_pUniBuff;
-    m_pUniBuff = new char16_t[wLen + 64];
-    m_uniBuffLen = wLen + 64;
-  }
-  if (wLen) {
-    MultiByteToWideChar(CP_ACP, 0, pStr, -1, wwc(m_pUniBuff), m_uniBuffLen);
-    result = m_pUniBuff;
-  }
+  NS_CopyNativeToUnicode(nsDependentCString(pStr), result);
 }
 
 BOOL CMapiApi::Initialize(void)
 {
   if (m_initialized)
     return TRUE;
 
   HRESULT    hr;
@@ -989,17 +972,18 @@ BOOL CMapiApi::IterateStores(CMapiFolder
         int         strLen = strlen(lpStr);
         char16_t * pwszStr = (char16_t *) moz_xmalloc((strLen + 1) * sizeof(WCHAR));
         if (!pwszStr) {
           // out of memory
           FreeProws(lpRow);
           lpTable->Release();
           return FALSE;
         }
-        ::MultiByteToWideChar(CP_ACP, 0, lpStr, strlen(lpStr) + 1, wwc(pwszStr), (strLen + 1) * sizeof(WCHAR));
+        ::MultiByteToWideChar(CP_ACP, 0, lpStr, strlen(lpStr) + 1,
+          reinterpret_cast<wchar_t*>(pwszStr), (strLen + 1) * sizeof(WCHAR));
         CMapiFolder *pFolder = new CMapiFolder(pwszStr, cbEID, lpEID, 0, MAPI_STORE);
         free(pwszStr);
 
         long szContents = 1;
         GetStoreInfo(pFolder, &szContents);
 
         MAPI_TRACE1("    DisplayName: %s\n", lpStr);
         if (szContents)

--- a/mailnews/import/outlook/src/MapiMessage.cpp
+++ b/mailnews/import/outlook/src/MapiMessage.cpp
@@ -628,18 +628,18 @@ void ExtractMetaCharset(const wchar_t* b
   // <META content="text/html; charset=utf-8" http-equiv=Content-Type>
   // <META content="text/html; charset=utf-8;" http-equiv=Content-Type>
   // <META content="text/html; charset=utf-8 ;" http-equiv=Content-Type>
   // <META content="text/html; charset=utf-8 " http-equiv=Content-Type>
   const wchar_t term[] = L";\" ", *term_end= term+sizeof(term)/sizeof(term[0])-1;
   const wchar_t* chset_end = std::find_first_of(chset_pos, eohd_pos, term,
                                                 term_end);
   if (chset_end != eohd_pos)
-    LossyCopyUTF16toASCII(Substring(wwc(const_cast<wchar_t *>(chset_pos)),
-                                    wwc(const_cast<wchar_t *>(chset_end))),
+    LossyCopyUTF16toASCII(Substring(char16ptr_t(chset_pos),
+                                    char16ptr_t(chset_end)),
                                     charset);
 }
 
 bool CMapiMessage::FetchBody(void)
 {
   m_bodyIsHtml = false;
   m_body.Truncate();
 

--- a/mailnews/mapi/mapihook/src/msgMapiImp.cpp
+++ b/mailnews/mapi/mapihook/src/msgMapiImp.cpp
@@ -162,17 +162,17 @@ STDMETHODIMP CMapiImp::Login(unsigned lo
     }
 
     // finally register(create) the session.
     uint32_t nSession_Id;
     int16_t nResult = 0;
 
     nsMAPIConfiguration *pConfig = nsMAPIConfiguration::GetMAPIConfiguration();
     if (pConfig != nullptr)
-        nResult = pConfig->RegisterSession(aUIArg, wwc(aLogin), wwc(aPassWord),
+        nResult = pConfig->RegisterSession(aUIArg, char16ptr_t(aLogin), char16ptr_t(aPassWord),
                                            (aFlags & MAPI_FORCE_DOWNLOAD), bNewSession,
                                            &nSession_Id, id_key.get());
     switch (nResult)
     {
         case -1 :
         {
             *aSessionId = MAPI_E_TOO_MANY_SESSIONS;
             return hr;