Golang sending emails over port 587 with InsecureSkipVerify.

smtp.go

package utils

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

var (
	smtpPort = "587"
	smtpHost = "example.com"
	smtpUser = "example@example.com"
	smtpAuth = smtp.PlainAuth("", smtpUser, "password", smtpHost)
)

func SendMail1(emails []string, body []byte) {
	if len(emails) < 1 {
		return
	}
	from := mail.Address{Address: smtpUser}
	body = append([]byte(fmt.Sprintf("From: %s\r\n", from.String())), body...)
	body = append([]byte(fmt.Sprintf("To: %s\r\n", strings.Join(emails, ","))), body...)

	smtpClient, err := smtp.Dial(fmt.Sprintf("%s:%s", smtpHost, smtpPort))
	if err != nil {
		panic(err)
	}
	defer smtpClient.Close()

	if ok, _ := smtpClient.Extension("STARTTLS"); ok {
		config := &tls.Config{ServerName: smtpHost, InsecureSkipVerify: true}
		if err = smtpClient.StartTLS(config); err != nil {
			panic(err)
		}
	}

	if err = smtpClient.Auth(smtpAuth); err != nil {
		panic(err)
	}

	if err = smtpClient.Mail(from.Address); err != nil {
		panic(err)
	}

	for _, addr := range emails {
		if err = smtpClient.Rcpt(addr); err != nil {
			panic(err)
		}
	}

	w, err := smtpClient.Data()
	if err != nil {
		panic(err)
	}

	_, err = w.Write(body)
	if err != nil {
		panic(err)
	}

	err = w.Close()
	if err != nil {
		panic(err)
	}
	smtpClient.Quit()

}