mail/internal/mail/smtp.go
func (d *Dialer) DialAndSend(m ...*Message) error {
	s, err := d.Dial()
	if err != nil {
		return err
	}
	defer s.Close()

	return Send(s, m...)
}
func (d *Dialer) DialAndSend(m ...*Message) error {
	s, err := d.Dial()
	if err != nil {
		return err
	}
	defer s.Close()

	return Send(s, m...)
}
// DialAndSend opens a connection to the SMTP server, sends the given emails and
// closes the connection.