If you want to open te default mail-client just declare the shellExecute API and call it:
Sub Email()
ret = ShellExecute(0&, vbNullString, "mailto: Perra@perra.es" ,vbNullString, "C:\", 1)
endSub
Private Declare Function ShellExecute Lib "shell32.dll" Alias "ShellExecuteA" (ByVal hWnd As Long, ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, ByVal lpDirectory As String, ByVal nShowCmd As Long) As Long