smtp/server.go
func (s *SMTP) SendMail(from string, to []string, msg []byte) (err error) {
	err = s.send(s.addr, s.auth, from, to, msg)
	return
}
func (s *SMTP) SendMail(from string, to []string, msg []byte) (err error) {
	err = s.send(s.addr, s.auth, from, to, msg)
	return
}
//SendMail send an email