电子邮件 SMTP 验证器 [英] Email SMTP validator

问题描述

我需要发送数百份时事通讯，但想先检查服务器上是否存在电子邮件.它被称为 SMTP 验证，至少我是这样认为的，基于我对 Internet 的研究.

I need to send hundreds of newsletters, but would like to check first if email exists on server. It's called SMTP validation, at least I think so, based on my research on Internet.

有几个库可以做到这一点，还有一个页面包含ASP Classic (http://www.coveryourasp.com/ValidateEmail.asp#Result3)，但是我很难读懂ASP Classic，而且它似乎使用了一些第三方库...

There's several libraries that can do that, and also a page with open-source code in ASP Classic (http://www.coveryourasp.com/ValidateEmail.asp#Result3), but I have hard time reading ASP Classic, and it seems that it uses some third-party library...

是否有一些 C# 中的 SMTP 验证代码，和/或它如何工作的一般解释?

Is there some code for SMTP validation in C#, and/or general explanation of how it works?

推荐答案

请注意，大多数 MTA(邮件传输代理)会出于垃圾邮件保护的原因关闭 VRFY 命令，如果您尝试多次，他们甚至可能会阻止您RCPT TO(参见 http://www.spamresource.com/2007/01/whatever-happened-to-vrfy.html).因此，即使您找到一个库来进行验证，也不会值很多钱.Ishmaeel 是对的，真正找出答案的唯一方法是发送电子邮件，看看它是否会被退回.

Be aware that most MTAs (Mail Transfer Agent) will have the VRFY command turned off for spam protection reasons, they'll probably even block you if you try several RCPT TO in a row (see http://www.spamresource.com/2007/01/whatever-happened-to-vrfy.html). So even if you find a library to do that verification, it won't be worth a lot. Ishmaeel is right, the only way to really find out, is sending an email and see if it bounces or not.

@Hrvoje:是的，我建议您监控被拒绝的电子邮件.但是:并非所有退回的邮件都会自动出现在您的不存在"列表中，您还必须区分临时(例如邮箱已满)和永久错误.

@Hrvoje: Yes, I'm suggesting you monitor rejected emails. BUT: not all the bounced mails should automatically end up on your "does not exist"-list, you also have to differentiate between temporary (e.g. mailbox full) and permanent errors.

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