golang smtp(email) ssl

使用golang发送邮件

参考

本文参考了github代码smtp ssl example及官方doc smtp示例

介绍

编写了一个struck支持ssl和非ssl发送邮件。本文使用了plain/text类型邮件

code

package email

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

//Client simple email client support ssl
type Client struct {
    user     string
    addr     string
    nickName string
    isSSL    bool
    auth     smtp.Auth
}

//New new email client
func New(user, password, nickName, host string, port int, isSsl bool) *Client {
    ec := &Client{
        user:  user,
        addr:  fmt.Sprintf("%s:%d", host, port),
        isSSL: isSsl,
        auth:  smtp.PlainAuth("", user, password, host),
    }
    if nickName == "" {
        ec.nickName = user
    } else {
        ec.nickName = nickName
    }
    return ec
}

func (ec *Client) generateEmailMsg(toUser []string, subject, content string) []byte {
    return ec.generateEmailMsgByte(toUser, subject, []byte(content))
}

func (ec *Client) generateEmailMsgByte(toUser []string, subject string, body []byte) []byte {
    msgStr := fmt.Sprintf("To: %s\r\nFrom: %s<%s>\r\nSubject: %s\r\nContent-Type: text/plain; charset=UTF-8\r\n\r\n",
        strings.Join(toUser, ","), ec.nickName, ec.user, subject)
    return append([]byte(msgStr), body...)
}

func (ec *Client) sendMailTLS(toUser []string, msg []byte) error {
    host, _, _ := net.SplitHostPort(ec.addr)
    tlsconfig := &tls.Config{
        InsecureSkipVerify: true,
        ServerName:         host,
    }
    conn, err := tls.Dial("tcp", ec.addr, tlsconfig)
    if err != nil {
        return fmt.Errorf("DialConn:%v", err)
    }
    client, err := smtp.NewClient(conn, host)
    if err != nil {
        return fmt.Errorf("Client:generateClient:%v", err)
    }
    defer client.Close()
    if ec.auth != nil {
        if ok, _ := client.Extension("AUTH"); ok {
            if err = client.Auth(ec.auth); err != nil {
                return fmt.Errorf("Client:clientAuth:%v", err)
            }
        }
    }
    if err = client.Mail(ec.user); err != nil {
        return fmt.Errorf("Client:clientMail:%v", err)
    }

    for _, addr := range toUser {
        if err = client.Rcpt(addr); err != nil {
            return fmt.Errorf("Client:Rcpt:%v", err)
        }
    }
    w, err := client.Data()
    if err != nil {
        return fmt.Errorf("Client:%v", err)
    }
    _, err = w.Write(msg)
    if err != nil {
        return fmt.Errorf("Client:WriterBody:%v", err)
    }
    err = w.Close()
    if err != nil {
        return fmt.Errorf("Client:CloseBody:%v", err)
    }
    return client.Quit()
}

func (ec *Client) sendMail(toUser []string, msg []byte) error {
    return smtp.SendMail(ec.addr, ec.auth, ec.user, toUser, msg)
}

//SendEmail send email by string content
func (ec *Client) SendEmail(toUser []string, subject string, content string) error {
    msg := ec.generateEmailMsg(toUser, subject, content)
    if ec.isSSL {
        return ec.sendMailTLS(toUser, msg)
    }
    return ec.sendMail(toUser, msg)
}

//SendEmailByte send email by byte body
func (ec *Client) SendEmailByte(toUser []string, subject string, body []byte) error {
    msg := ec.generateEmailMsgByte(toUser, subject, body)
    if ec.isSSL {
        return ec.sendMailTLS(toUser, msg)
    }
    return ec.sendMail(toUser, msg)
}

测试

import "fmt"
func main(){
  client := New("[email protected]", "xxxxxx", "username", "mail.example.com", 465, true)
  if err := client.SendEmail([]string{"[email protected]"},"email send test","this is a test email for sending.\r\nJust Testing");err !=nil{
    fmt.Println(err)
  }
}