Private Sub txtEMail_DblClick()
    Dim rc As Long
    Dim emailAddress As String
 
    On Error GoTo failEmail
 
    emailAddress = txtEmail.text
 
        rc = ShellExecute(Me.hwnd, "Open", _
          "mailto:Name@domain.de?Subject=", "", "", SW_SHOWNORMAL)
 
failEmail:
 
...  
 
End Sub