Const ERROR_NO_MORE_ITEMS = 259&
Const HKEY_CURRENT_USER = &H80000001
Private Declare Function RegCloseKey Lib "advapi32.dll" (ByVal hKey As Long) As _
  Long
Private Declare Function RegOpenKey Lib "advapi32.dll" Alias "RegOpenKeyA" ( _
ByVal hKey As Long, ByVal lpSubKey As String, phkResult As Long) As Long
Private Declare Function RegEnumKeyEx Lib "advapi32.dll" Alias "RegEnumKeyExA" ( _
ByVal hKey As Long, ByVal dwIndex As Long, ByVal lpName As String, lpcbName As _
Long, ByVal lpReserved As Long, ByVal lpClass As String, lpcbClass As Long, _
lpftLastWriteTime As Any) As Long
 
Private Sub Command1_Click()
  Dim hKey As Long
  Dim Cnt As Long
  Dim sName As String
  Dim Ret As Long
  Const BUFFER_SIZE As Long = 255
  Ret = BUFFER_SIZE
  sName = Space(BUFFER_SIZE)
  RegOpenKey HKEY_CURRENT_USER, "Software\Microsoft\Internet Account" & _
    "Manager\Accounts", hKey
  While RegEnumKeyEx(hKey, Cnt, sName, Ret, ByVal 0&, vbNullString, ByVal 0&, _
  ByVal 0&)  ERROR_NO_MORE_ITEMS
    If Format(Val(Mid(sName, 1, Ret)), "00000000")  "00000000" Then
      Combo1.AddItem Mid(sName, 1, Ret)
    End If
    Ret = BUFFER_SIZE
    Cnt = Cnt + 1
  Wend
  RegCloseKey hKey
End Sub