Go Simple Mail

The best way to send emails in Go with SMTP Keep Alive and Timeout for Connect and Send.

IMPORTANT

Examples in this README are for v2.2.0 and above. Examples for older versions can be found here.

The minimum Go version is 1.13, for Go 1.12 and older use branch go1.12.

Breaking change in 2.2.0: The signature of SetBody and AddAlternative used to accept strings ("text/html" and "text/plain") and not require on of the contentType constants (TextHTML or TextPlain). Upgrading, while not quite following semantic versioning, is quite simple:

  email := mail.NewMSG()
- email.SetBody("text/html", htmlBody)
- email.AddAlternative("text/plain", plainBody)
+ email.SetBody(mail.TextHTML, htmlBody)
+ email.AddAlternative(mail.TextPlain, plainBody)

Introduction

Go Simple Mail is a simple and efficient package to send emails. It is well tested and documented.

Go Simple Mail can only send emails using an SMTP server. But the API is flexible and it is easy to implement other methods for sending emails using a local Postfix, an API, etc.

This package contains (and is based on) two packages by Joe Grasse:

https://github.com/joegrasse/mail (unmaintained since Jun 29, 2018), and
https://github.com/joegrasse/mime (unmaintained since Oct 1, 2015).

A lot of changes in Go Simple Mail were sent with not response.

Features

Go Simple Mail supports:

Multiple Attachments with path
Multiple Attachments in base64
Multiple Recipients
Priority
Reply to
Set other sender
Set other from
Embedded images
HTML and text templates
Automatic encoding of special characters
SSL and TLS
Unencrypted connection (not recommended)
Sending multiple emails with the same SMTP connection (Keep Alive or Persistent Connection)
Timeout for connect to a SMTP Server
Timeout for send an email
Return Path
Alternative Email Body
CC and BCC
Add Custom Headers in Message
Send NOOP, RESET, QUIT and CLOSE to SMTP client
PLAIN, LOGIN and CRAM-MD5 Authentication (since v2.3.0)
Custom TLS Configuration (since v2.5.0)

Documentation

https://pkg.go.dev/github.com/xhit/go-simple-mail/v2?tab=doc

Download

This package uses go modules.

$ go get github.com/xhit/go-simple-mail/v2

Usage

package main

import (
	"log"

	"github.com/xhit/go-simple-mail/v2"
)

const htmlBody = `<html>
	<head>
		<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
		<title>Hello Gophers!</title>
	</head>
	<body>
		<p>This is the <b>Go gopher</b>.</p>
		<p><img src="cid:Gopher.png" alt="Go gopher" /></p>
		<p>Image created by Renee French</p>
	</body>
</html>`

func main() {
	server := mail.NewSMTPClient()

	// SMTP Server
	server.Host = "smtp.example.com"
	server.Port = 587
	server.Username = "test@example.com"
	server.Password = "examplepass"
	server.Encryption = mail.EncryptionTLS

	// Since v2.3.0 you can specified authentication type:
	// - PLAIN (default)
	// - LOGIN
	// - CRAM-MD5
	// server.Authentication = mail.AuthPlain

	// Variable to keep alive connection
	server.KeepAlive = false

	// Timeout for connect to SMTP Server
	server.ConnectTimeout = 10 * time.Second

	// Timeout for send the data and wait respond
	server.SendTimeout = 10 * time.Second

	// Set TLSConfig to provide custom TLS configuration. For example,
	// to skip TLS verification (useful for testing):
	server.TLSConfig = &tls.Config{InsecureSkipVerify: true}

	// SMTP client
	smtpClient,err := server.Connect()

	if err != nil{
		log.Fatal(err)
	}

	// New email simple html with inline and CC
	email := mail.NewMSG()
	email.SetFrom("From Example <nube@example.com>").
		AddTo("xhit@example.com").
		AddCc("otherto@example.com").
		SetSubject("New Go Email")

	email.SetBody(mail.TextHTML, htmlBody)

	email.AddInline("/path/to/image.png", "Gopher.png")

	// Call Send and pass the client
	err = email.Send(smtpClient)
	if err != nil {
		log.Println(err)
	} else {
		log.Println("Email Sent")
	}
}

Send multiple emails in same connection

	//Set your smtpClient struct to keep alive connection
	server.KeepAlive = true

	for _, to := range []string{
		"to1@example1.com",
		"to3@example2.com",
		"to4@example3.com",
	} {
		// New email simple html with inline and CC
		email := mail.NewMSG()
		email.SetFrom("From Example <nube@example.com>").
			AddTo(to).
			SetSubject("New Go Email")

		email.SetBody(mail.TextHTML, htmlBody)
		email.AddInline("/path/to/image.png", "Gopher.png")

		// Call Send and pass the client
		err = email.Send(smtpClient)
		if err != nil {
			log.Println(err)
		} else {
			log.Println("Email Sent")
		}
	}

More examples

See example/example_test.go.

falconandy/go-simple-mail