bash 和 telnet 来测试电子邮件

Question

我正在尝试查明电子邮件地址是否有效。

我已经通过 telnet 完成了这个，见下文

$ telnet mail.example.com 25
Trying 0.0.0.0...
Connected to mail.example.com.
Escape character is '^]'.
220 mail.example.com Mon, 14 Jan 2013 19:01:44 +0000
helo email.com
250 mail.example.com Hello email.com [0.0.0.0]
mail from:blake@email.com
250 OK
rcpt to:gfdgsdfhgsfd@example.com
550 Unknown user

通过这个 550 请求，我知道该地址在邮件服务器上无效...如果有效，我会得到如下响应:

250 2.1.5 OK 

我如何在 shell 脚本中自动执行此操作？到目前为止，我有以下内容

#!/bin/bash
host=`dig mx +short $1 | cut -d ' ' -f2 | head -1`
telnet $host 25 

谢谢!

Answer 1

尝试这样做:

[[ $4 ]] || {
    printf "Usage\n\t$0 <domain> <email> <from_email> <rcpt_email>\n"
    exit 1
}
{
    sleep 1
    echo "helo $2"
    sleep 0.5
    echo "mail from:<$3>"
    sleep 0.5
    echo "rcpt to:<$4>"
    echo
} | telnet $1 25 |
    grep -q "Unknown user" &&
    echo "Invalid email" ||
    echo "Valid email"

用法:

./script.sh domain email from_email rcpt_email