Anton F

import (
// ...
	gomail "gopkg.in/gomail.v2"
)

func makeMailer() (*gomail.Dialer, error) {
	smtp := "SMTP_MAIL_ADDRESS"
	port, err := strconv.Atoi("PORT_NUM")
	if err != nil {
		fmt.Println("error parsing smtp port.", err)
		return nil, err
	}
	name := "MAILER_AUTH_NAME"
	pwd := "MAILER_AUTH_PWD"
	if port == 0 || smtp == "" && name == "" {
		return nil, errors.New("invalid mailer parameters")
	}

	return gomail.NewDialer(smtp, port, name, pwd), nil
}

func send() (*..., error) {
	mailer, err := makeMailer()
	if err != nil {
		return nil, fmt.Errorf("can't create mailer. %v", err)
	}

	recipient := "MAILER_RECIPIENT"
	if recipient == "" {
		return nil, fmt.Errorf("empty recipient")
	}

	m := gomail.NewMessage()
	m.SetHeader("From", "MAILER_AUTH_NAME")
	m.SetHeader("To", "MAILER_RECIPIENT")
	m.SetHeader("Subject", "MAILER_SUBJECT")
	m.SetBody("text/plain", "MAIL_BODY_TEXT")

	err = mailer.DialAndSend(m)
	if err != nil {
		return nil, fmt.Errorf("can't send digest. %v", err)
	}
}