How to send emails in Golang

package main

import (
    "fmt"
    "net/smtp"
)

package main

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

// Main function
func  main() {
    // from is sender's email address
    from := os.Getenv("MAIL")
    password := os.Getenv("PASSWD")

    // toList is a list of email addresses that email is to be sent
    toList := []string{"example@gmail.com"}

    // host is address of server that the  sender's email address belongs,
    // in this case it's gmail.
    host := "smtp.gmail.com"

    // It's the default port of smtp server
    port := "587"

    // This is the message to send in the mail
    msg := "Hello World!"

    // We can't send strings directly in mail,
    // strings need to be converted into slice bytes
    body := []byte(msg)

    // PlainAuth uses the given username and password to
    // authenticate to host and act as identity.
    auth := smtp.PlainAuth("", from, password, host)

    // SendMail uses TLS connection to send the mail
    // The email is sent to all address in the toList,
    // the body should be of type bytes, not strings
    // This returns an error if any occurred.
    err := smtp.SendMail(host+":"+port, auth, from, toList, body)

    // handling the errors
    if err != nil { 
        fmt.Println(err)
        os.Exit(1)
    }

    fmt.Println("Successfully sent email!")
}

package main

import (
    "crypto/tls"
    "fmt"
    gomail "gopkg.in/mail.v2"
)

package main

import (
    "crypto/tls"
    "fmt"
    gomail "gopkg.in/mail.v2"
)

func main() {
    m := gomail.NewMessage()

    m.SetHeader("From", "youremail@gmail.com")
    m.SetHeader("To", "recipient@example.com")

    m.SetHeader("Subject", "Sending Email with Goalang")

    // Set the email body. You can set plain text or html with text/html
    m.SetBody("text/plain", "Hello World!")

    // Settings for SMTP server
    d := gomail.NewDialer("smtp.gmail.com", 587, "youremail@gmail.com", "yourpassword")

    // This is only needed when the SSL/TLS certificate is not valid on the server.
    // In production this should be set to false.
    d.TLSConfig = &tls.Config{InsecureSkipVerify: true}

    if err := d.DialAndSend(m); err != nil {
        fmt.Println(err)
        panic(err)
    }

    return
}