可能重复：   How检查电子邮件地址不存在发送电子邮件？

您如何检查电子邮件地址实际存在（不只是验证）？如何做这些家伙做： http://www.email-unlimited.com/工具/验证，email.aspx

How can you check if an email address actually exists (not just validating)? How do these guys do it: http://www.email-unlimited.com/tools/verify-email.aspx

看来工作...

推荐答案

SMTP协议具有接收服务器上的邮箱和的可以的，如果返回一个OKcode命令RCPT该邮箱存在。请注意，有些服务器并不在顺序扫描的有效地址，这样做是为了prevent垃圾邮件发送者。

The SMTP protocol has the command RCPT that receives a mailbox on the server and may return an "ok" code if that mailbox exists. Note that some servers don't do this in order to prevent spammers from scanning for valid addresses.

什么电子邮件无限做的是以下内容：

What email-unlimited do is the following:

如果SMTP服务器在步骤2中返回一个OKcode，然后他们决定信箱存在。

If the SMTP server returns an "ok" code in step 2, then they decide that the mailbox exists.