Prova con questo :
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
Const SW_SHOWNORMAL = 1
Private Sub Pippo()
    ShellExecute Me.hwnd, "open", "http://www.iltuosito.com", vbNullString, vbNullString, SW_SHOWNORMAL
    ShellExecute Me.hwnd, "open", "mailto:
[email protected]", vbNullString, vbNullString, SW_SHOWNORMAL
End Sub