Sending email using Go

email.go

package main

import (
        "fmt"
        "github.com/alexcesaro/mail/gomail"
        "net/smtp"
)

type Email struct {
        From       string
        FromName   string
        To         []string
        Subject    string
        Body       string
        HTML       string
        Attachment string

        Server   string
        UserName string
        Password string
        Port     uint16
}

func full_host(email Email) string {
        return fmt.Sprintf("%s:%d", email.Server, email.Port)
}

func Natural_Mail(email Email) error {
        auth := smtp.PlainAuth("", email.UserName, email.Password, email.Server)

        host := full_host(email)
        msg := []byte("Subject: " + email.Subject + "\r\n\r\n" + email.Body)
        return smtp.SendMail(host, auth, email.From, email.To, msg)
}

func Go_Mail(email Email) error {
        msg := gomail.NewMessage()
        msg.SetAddressHeader("From", email.From, email.FromName)
        for i, v := range email.To {
                if i == 0 {
                        msg.SetHeader("To", v)
                } else {
                        msg.AddHeader("To", v)
                }
        }
        msg.SetHeader("Subject", email.Subject)
        msg.SetBody("text/plain", email.Body)
        if email.HTML != "" {
                msg.AddAlternative("text/html", email.HTML)
        }

        if email.Attachment != "" {
                err := msg.Attach(email.Attachment)
                if err != nil {
                        return err
                }
        }

        var m gomail.Mailer
        if email.Port != 25 {
                auth := smtp.PlainAuth("", email.UserName, email.Password, email.Server)
                host := full_host(email)
                m = gomail.NewCustomMailer(auth, host)
        } else {
                m = gomail.NewMailer(email.Server, email.UserName, email.Password, int(email.Port))
        }

        return m.Send(msg)
}

func main() {
        email := Email{
                From:     "alice@example.com",
                FromName: "Alice",
                To:       []string{"bob@example.com", "cat@example.com"},
                Subject:  "Testing email using Go",
                Body:     "Testing email using Go",
                HTML: "<h1>Welcome</h1><br>\n" +
                        "Testing email using Go",

                Server:   "smtp.gmail.com",
                UserName: "alice",
                Password: "password",
                Port:     25,
        }

        fmt.Println("Going to use Go_Mail")
        err := Go_Mail(email)

        if err != nil {
                fmt.Printf("Unable to send email using Go_Mail: %s", err)
        }

        fmt.Println("Going to use Natural_Mail")
        err = Natural_Mail(email)

        if err != nil {
                fmt.Printf("Unable to send email using Natural_Mail: %s", err)
        }
}