smtp

package standard library
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 Go to latest Published: Jan 4, 2023 License: BSD-3-Clause Imports: 10 Imported by: 12,353

Documentation

Overview

Package smtp implements the Simple Mail Transfer Protocol as defined in RFC 5321. It also implements the following extensions: 

8BITMIME  RFC 1652
AUTH      RFC 2554
STARTTLS  RFC 3207

Additional extensions may be handled by clients.

The smtp package is frozen and is not accepting new features. Some external packages provide more functionality. See: 

https://godoc.org/?q=smtp
Example 
package main

import (
	"fmt"
	"log"
	"net/smtp"
)

func main() {
	// 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"); err != nil {
		log.Fatal(err)
	}
	if err := c.Rcpt("recipient@example.net"); 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)
	}
}

Index

Examples

Constants

This section is empty.

Variables

This section is empty.

Functions

func SendMail 

func SendMail(addr string, a Auth, from string, to []string, msg []byte) error

SendMail connects to the server at addr, switches to TLS if possible, authenticates with the optional mechanism a if possible, and then sends an email from address from, to addresses to, with message msg. The addr must include a port, as in "mail.example.com:smtp".

The addresses in the to parameter are the SMTP RCPT addresses.

The msg parameter should be an RFC 822-style email with headers first, a blank line, and then the message body. The lines of msg should be CRLF terminated. The msg headers should usually include fields such as "From", "To", "Subject", and "Cc". Sending "Bcc" messages is accomplished by including an email address in the to parameter but not including it in the msg headers.

The SendMail function and the net/smtp package are low-level mechanisms and provide no support for DKIM signing, MIME attachments (see the mime/multipart package), or other mail functionality. Higher-level packages exist outside of the standard library.

Example 
package main

import (
	"log"
	"net/smtp"
)

func main() {
	// Set up authentication information.
	auth := smtp.PlainAuth("", "user@example.com", "password", "mail.example.com")

	// Connect to the server, authenticate, set the sender and recipient,
	// and send the email all in one step.
	to := []string{"recipient@example.net"}
	msg := []byte("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)
	}
}

Types

type Auth 

type Auth interface {
	// Start begins an authentication with a server.
	// It returns the name of the authentication protocol
	// and optionally data to include in the initial AUTH message
	// sent to the server.
	// If it returns a non-nil error, the SMTP client aborts
	// the authentication attempt and closes the connection.
	Start(server *ServerInfo) (proto string, toServer []byte, err error)

	// Next continues the authentication. The server has just sent
	// the fromServer data. If more is true, the server expects a
	// response, which Next should return as toServer; otherwise
	// Next should return toServer == nil.
	// If Next returns a non-nil error, the SMTP client aborts
	// the authentication attempt and closes the connection.
	Next(fromServer []byte, more bool) (toServer []byte, err error)
}

Auth is implemented by an SMTP authentication mechanism.

func