go-smtp/example_test.go

// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package smtp_test

import (
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"strings"
	"time"

	"github.com/emersion/go-sasl"
	"github.com/emersion/go-smtp"
)

func ExampleDial() {
	// Connect to the remote SMTP server.
	c, err := smtp.Dial("mail.example.com:25")
	if err != nil {
		log.Fatal(err)
	}

	// Set the sender and recipient first
	if err := c.Mail("sender@example.org", nil); err != nil {
		log.Fatal(err)
	}
	if err := c.Rcpt("recipient@example.net", nil); err != nil {
		log.Fatal(err)
	}

	// Send the email body.
	wc, err := c.Data()
	if err != nil {
		log.Fatal(err)
	}
	_, err = fmt.Fprintf(wc, "This is the email body")
	if err != nil {
		log.Fatal(err)
	}
	err = wc.Close()
	if err != nil {
		log.Fatal(err)
	}

	// Send the QUIT command and close the connection.
	err = c.Quit()
	if err != nil {
		log.Fatal(err)
	}
}

// variables to make ExamplePlainAuth compile, without adding
// unnecessary noise there.
var (
	from       = "gopher@example.net"
	msg        = strings.NewReader("dummy message")
	recipients = []string{"foo@example.com"}
)

func ExampleSendMail_PlainAuth() {
	// hostname is used by PlainAuth to validate the TLS certificate.
	hostname := "mail.example.com"
	auth := sasl.NewPlainClient("", "user@example.com", "password")

	err := smtp.SendMail(hostname+":25", auth, from, recipients, msg)
	if err != nil {
		log.Fatal(err)
	}
}

func ExampleSendMail() {
	// Set up authentication information.
	auth := sasl.NewPlainClient("", "user@example.com", "password")

	// Connect to the server, authenticate, set the sender and recipient,
	// and send the email all in one step.
	to := []string{"recipient@example.net"}
	msg := strings.NewReader("To: recipient@example.net\r\n" +
		"Subject: discount Gophers!\r\n" +
		"\r\n" +
		"This is the email body.\r\n")
	err := smtp.SendMail("mail.example.com:25", auth, "sender@example.org", to, msg)
	if err != nil {
		log.Fatal(err)
	}
}

// The Backend implements SMTP server methods.
type Backend struct{}

// NewSession is called after client greeting (EHLO, HELO).
func (bkd *Backend) NewSession(c *smtp.Conn) (smtp.Session, error) {
	return &Session{}, nil
}

// A Session is returned after successful login.
type Session struct{}

// AuthPlain implements authentication using SASL PLAIN.
func (s *Session) AuthPlain(username, password string) error {
	if username != "username" || password != "password" {
		return errors.New("Invalid username or password")
	}
	return nil
}

func (s *Session) Mail(from string, opts *smtp.MailOptions) error {
	log.Println("Mail from:", from)
	return nil
}

func (s *Session) Rcpt(to string, opts *smtp.RcptOptions) error {
	log.Println("Rcpt to:", to)
	return nil
}

func (s *Session) Data(r io.Reader) error {
	if b, err := ioutil.ReadAll(r); err != nil {
		return err
	} else {
		log.Println("Data:", string(b))
	}
	return nil
}

func (s *Session) Reset() {}

func (s *Session) Logout() error {
	return nil
}

func ExampleNewServer() {
	be := &Backend{}

	s := smtp.NewServer(be)

	s.Addr = ":1025"
	s.Domain = "localhost"
	s.WriteTimeout = 10 * time.Second
	s.ReadTimeout = 10 * time.Second
	s.MaxMessageBytes = 1024 * 1024
	s.MaxRecipients = 50
	s.AllowInsecureAuth = true

	log.Println("Starting server at", s.Addr)
	if err := s.ListenAndServe(); err != nil {
		log.Fatal(err)
	}
}