检查SMTP服务器是否在线

Question

如何检查 SMTP 是否在线并正在运行？

func (p *sys_ping) smtp(host string) string {
    client, err := smtp.Dial(host)
    if err != nil {
        time.Sleep(time.Duration(p.delay) * time.Second)
        return ""
    }
// check if response code is 220 or something similar to check if server is running
    client.Quit()
    return host
}

上面的代码是连接SMTP。有用。但是如何检查响应代码是否为

220

？我猜正确的代码应该是

220

来检查服务器是否运行正确？

Answer 1

是的，服务器应该响应代码 220 才能接受连接

 import (
        "net/smtp"
        "time"
        "strings"
    )
    
    func (p *sys_ping) smtp(host string) string {
        client, err := smtp.Dial(host)
        if err != nil {
            time.Sleep(time.Duration(p.delay) * time.Second)
            return ""
        }
        defer client.Quit()
    
        // Read initial resp code from server
        response, err := client.Text.ReadResponse(220)
        if err != nil || !strings.HasPrefix(response, "220") {
            return ""
        }
    
        return host
    }