guinso/main.go

## main.go
package main

import (
	"crypto/tls"
	"fmt"
	"log"
	"net/smtp"
	"strings"
)

//https://hackernoon.com/golang-sendmail-sending-mail-through-net-smtp-package-5cadbe2670e0
func main() {
	var (
		serverAddr = "smtp.gmail.com"
		password   = "your-password"
		emailAddr  = "your-email@gmail.com"
		portNumber = 465
		tos        = []string{
			"friendA@yahoo.com",
			"friendB@hotmail.com",
		}
		cc = []string{
			"friendC@yandex.com",
		}
	)

	log.Println("======= Test Gmail client =========")
	log.Println("NOTE: user need to turn on 'less secure apps' options")
	log.Println("URL:  https://myaccount.google.com/lesssecureapps\n\r")

	tlsConfig := tls.Config{
		ServerName:         serverAddr,
		InsecureSkipVerify: true,
	}

	log.Println("Establish TLS connection")
	conn, connErr := tls.Dial("tcp", fmt.Sprintf("%s:%d", serverAddr, portNumber), &tlsConfig)
	if connErr != nil {
		log.Panic(connErr)
	}
	defer conn.Close()

	log.Println("create new email client")
	client, clientErr := smtp.NewClient(conn, serverAddr)
	if clientErr != nil {
		log.Panic(clientErr)
	}
	defer client.Close()

	log.Println("setup authenticate credential")
	auth := smtp.PlainAuth("", emailAddr, password, serverAddr)

	if err := client.Auth(auth); err != nil {
		log.Panic(err)
	}

	log.Println("Start write mail content")
	log.Println("Set 'FROM'")
	if err := client.Mail(emailAddr); err != nil {
		log.Panic(err)
	}
	log.Println("Set 'TO(s)'")
	for _, to := range tos {
		if err := client.Rcpt(to); err != nil {
			log.Panic(err)
		}
	}

	writer, writerErr := client.Data()
	if writerErr != nil {
		log.Panic(writerErr)
	}

	//basic email headers
	sampleMsg := fmt.Sprintf("From: %s\r\n", emailAddr)
	sampleMsg += fmt.Sprintf("To: %s\r\n", strings.Join(tos, ";"))
	if len(cc) > 0 {
		sampleMsg += fmt.Sprintf("Cc: %s\r\n", strings.Join(cc, ";"))
	}
	sampleMsg += fmt.Sprintf("Subject: %s\r\n", "Golang example send mail in HTML format")

	//enable HTML format message
	sampleMsg += "Mime-Version: 1.0\r\n"
	sampleMsg += "Content-Type: text/html; charset=\"utf-8\""
	sampleMsg += "Content-Transfer-Encoding: 7bit"

	//email message
	sampleMsg += fmt.Sprintf("\r\n%s", "<html><body><h1>Hi There</h1>"+
		"<p>this is sample email sent via golang program</p></body></html>")

	log.Println("Write content into client writter I/O")
	if _, err := writer.Write([]byte(sampleMsg)); err != nil {
		log.Panic(err)
	}

	if closeErr := writer.Close(); closeErr != nil {
		log.Panic(closeErr)
	}

	client.Quit()

	log.Print("done.")
}
	package main

	import (
	"crypto/tls"
	"fmt"
	"log"
	"net/smtp"
	"strings"
	)

	//https://hackernoon.com/golang-sendmail-sending-mail-through-net-smtp-package-5cadbe2670e0
	func main() {
	var (
	serverAddr = "smtp.gmail.com"
	password = "your-password"
	emailAddr = "your-email@gmail.com"
	portNumber = 465
	tos = []string{
	"friendA@yahoo.com",
	"friendB@hotmail.com",
	}
	cc = []string{
	"friendC@yandex.com",
	}
	)

	log.Println("======= Test Gmail client =========")
	log.Println("NOTE: user need to turn on 'less secure apps' options")
	log.Println("URL: https://myaccount.google.com/lesssecureapps\n\r")

	tlsConfig := tls.Config{
	ServerName: serverAddr,
	InsecureSkipVerify: true,
	}

	log.Println("Establish TLS connection")
	conn, connErr := tls.Dial("tcp", fmt.Sprintf("%s:%d", serverAddr, portNumber), &tlsConfig)
	if connErr != nil {
	log.Panic(connErr)
	}
	defer conn.Close()

	log.Println("create new email client")
	client, clientErr := smtp.NewClient(conn, serverAddr)
	if clientErr != nil {
	log.Panic(clientErr)
	}
	defer client.Close()

	log.Println("setup authenticate credential")
	auth := smtp.PlainAuth("", emailAddr, password, serverAddr)

	if err := client.Auth(auth); err != nil {
	log.Panic(err)
	}

	log.Println("Start write mail content")
	log.Println("Set 'FROM'")
	if err := client.Mail(emailAddr); err != nil {
	log.Panic(err)
	}
	log.Println("Set 'TO(s)'")
	for _, to := range tos {
	if err := client.Rcpt(to); err != nil {
	log.Panic(err)
	}
	}

	writer, writerErr := client.Data()
	if writerErr != nil {
	log.Panic(writerErr)
	}

	//basic email headers
	sampleMsg := fmt.Sprintf("From: %s\r\n", emailAddr)
	sampleMsg += fmt.Sprintf("To: %s\r\n", strings.Join(tos, ";"))
	if len(cc) > 0 {
	sampleMsg += fmt.Sprintf("Cc: %s\r\n", strings.Join(cc, ";"))
	}
	sampleMsg += fmt.Sprintf("Subject: %s\r\n", "Golang example send mail in HTML format")

	//enable HTML format message
	sampleMsg += "Mime-Version: 1.0\r\n"
	sampleMsg += "Content-Type: text/html; charset=\"utf-8\""
	sampleMsg += "Content-Transfer-Encoding: 7bit"

	//email message
	sampleMsg += fmt.Sprintf("\r\n%s", "<html><body><h1>Hi There</h1>"+
	"<p>this is sample email sent via golang program</p></body></html>")

	log.Println("Write content into client writter I/O")
	if _, err := writer.Write([]byte(sampleMsg)); err != nil {
	log.Panic(err)
	}

	if closeErr := writer.Close(); closeErr != nil {
	log.Panic(closeErr)
	}

	client.Quit()

	log.Print("done.")
	}