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    SMTP-Go

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    SMTP-Go

    Last Updated: Sep 03, 2018

    The following example shows how to send an email through SMTP using the Go language(Version 1.9).

    1. package main
    3. import (
    4.     "fmt"
    5.     "net/smtp"
    6.     "strings"
    7. )
    9. func SendToMail(user, password, host, to, subject, body, mailtype string) error {
    10.     hp := strings.Split(host, ":")
    11.     auth := smtp.PlainAuth("", user, password, hp[0])
    12.     var content_type string
    13.     if mailtype == "html" {
    14.         content_type = "Content-Type: text/" + mailtype + "; charset=UTF-8"
    15.     } else {
    16.         content_type = "Content-Type: text/plain" + "; charset=UTF-8"
    17.     }
    19.     msg := []byte("To: " + to + "\r\nFrom: " + user + "\r\nSubject: " + subject + "\r\n" + content_type + "\r\n\r\n" + body)
    20.     send_to := strings.Split(to, ";")
    21.     err := smtp.SendMail(host, auth, user, send_to, msg)
    22.     return err
    23. }
    25. func main() {
    26.     user := "The mail address created in the console"
    27.     password := "The SMTP password set in the console"
    28.     host := "smtpdm.aliyun.com:25"
    29.     to := "Destination address"
    31.     subject := "test Golang to sendmail"
    33.     body := `
    34.         <html>
    35.         <body>
    36.         <h3>
    37.         "Test send to email"
    38.         </h3>
    39.         </body>
    40.         </html>
    41.         `
    42.     fmt.Println("send email")
    43.     err := SendToMail(user, password, host, to, subject, body, "html")
    44.     if err != nil {
    45.         fmt.Println("Send mail error!")
    46.         fmt.Println(err)
    47.     } else {
    48.         fmt.Println("Send mail success!")
    49.     }
    51. }

    If your Go language Version is 1.9.2, errors such as “unencrypted connection” may come about. This version demands LoginAuth with encrytion and here is the addition:

    1. type loginAuth struct {
    2.     username, password string
    3. }
    4. func LoginAuth(username, password string) smtp.Auth {
    5.     return &loginAuth{username, password}
    6. }
    7. func (a *loginAuth) Start(server *smtp.ServerInfo) (string, []byte, error) {
    8.     // return "LOGIN", []byte{}, nil
    9.     return "LOGIN", []byte(a.username), nil
    10. }
    11. func (a *loginAuth) Next(fromServer []byte, more bool) ([]byte, error) {
    12.     if more {
    13.         switch string(fromServer) {
    14.         case "Username:":
    15.             return []byte(a.username), nil
    16.         case "Password:":
    17.             return []byte(a.password), nil
    18.         }
    19.     }
    20.     return nil, nil
    21. }

    Then change auth method to the following:

    1. auth := LoginAuth(user, password)