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Sample Call for Go

Last updated: 2023-12-22 10:27:45

The following sample code uses SMTP to send an email in Go language (v1.16):
package main
﻿
import (
    "crypto/tls"
    "fmt"
    "log"
    "net"
    "net/smtp"
)
﻿
// Test465  for port 465
func Test465() error {
    host := "sg-smtp.qcloudmail.com"
    port := 465
    // Sender address created in the console
    email := "abc@cd.com" 
    // SMTP password set in the console
    password := "****"
    toEmail := "test@test123.com"
    header := make(map[string]string)
    header["From"] = "test " + "<" + email + ">"
    header["To"] = toEmail
    header["Subject"] = "test subject"
    // HTML email
    header["Content-Type"] = "text/html; charset=UTF-8"
    body := "<!DOCTYPE html>\\n<html>\\n<head>\\n<meta charset=\\"utf-8\\">\\n<title>hello world</title>\\n</head>\\n<body>\\n " +
        "<h1>My first heading</h1>\\n    <p>My first paragraph.</p>\\n</body>\\n</html>"
    // Plain text email
    //header["Content-Type"] = "text/plain; charset=UTF-8"
    //body := "test body"
    message := ""
    for k, v := range header {
        message += fmt.Sprintf("%s: %s\\r\\n", k, v)
    }
    message += "\\r\\n" + body
    auth := smtp.PlainAuth(
        "",
        email,
        password,
        host,
    )
    err := SendMailWithTLS(
        fmt.Sprintf("%s:%d", host, port),
        auth,
        email,
        []string{toEmail},
        []byte(message),
    )
    if err != nil {
        fmt.Println("Send email error:", err)
    } else {
        fmt.Println("Send mail success!")
    }
    return err
}
﻿
// Dial return a smtp client
func Dial(addr string) (*smtp.Client, error) {
    conn, err := tls.Dial("tcp", addr, nil)
    if err != nil {
        log.Println("tls.Dial Error:", err)
        return nil, err
    }
﻿
    host, _, _ := net.SplitHostPort(addr)
    return smtp.NewClient(conn, host)
}
﻿
// SendMailWithTLS send email with tls
func SendMailWithTLS(addr string, auth smtp.Auth, from string,
    to []string, msg []byte) (err error) {
    //create smtp client
    c, err := Dial(addr)
    if err != nil {
        log.Println("Create smtp client error:", err)
        return err
    }
    defer c.Close()
    if auth != nil {
        if ok, _ := c.Extension("AUTH"); ok {
            if err = c.Auth(auth); err != nil {
                log.Println("Error during AUTH", err)
                return err
            }
        }
    }
    if err = c.Mail(from); err != nil {
        return err
    }
    for _, addr := range to {
        if err = c.Rcpt(addr); err != nil {
            return err
        }
    }
    w, err := c.Data()
    if err != nil {
        return err
    }
    _, err = w.Write(msg)
    if err != nil {
        return err
    }
    err = w.Close()
    if err != nil {
        return err
    }
    return c.Quit()
}
﻿
func main() {
    Test465()
}