电子邮件验证MX Lookup [英] Email validation MX Lookup

问题描述

我被要求在网络应用程序上实施一些电子邮件地址验证 - 我相信我们已经有一千次了...但是，这次我被要求在域上进行MX查询看看它是否接受电子邮件。

I have been asked to implement some email address validation on a web app - I'm sure we've all been there a thousand times... however, this time I have been asked to do an MX Lookup on the domain to see if it accepts emails.

有没有人知道这样做有什么潜在的问题？一个mx查询是一个可靠的方式来查找一个域是否接受电子邮件？有没有一个有效的电子邮件地址可能无法进行MX查询检查的边缘案例？

Does anyone know of any potential problems with doing this? Is an mx lookup a reliable way of finding out if a domain accepts email? are there any edge cases where a valid email address could fail an MX lookup check?

感谢您的建议！

推荐答案

是否有任何边缘案例，有效的电子邮件地址可能会失败MX查找检查？ / p>

are there any edge cases where a valid email address could fail an MX lookup check?

是的，在没有MX记录的情况下，MTA会回到使用A记录。因此，只允许MX记录将失败一类在现实世界中工作的邮件服务器。

Yes, in that where there is no MX record, MTAs fall back to using the A record instead. So only allowing MX records would fail a class of mail servers that work in the real world.

允许使用MX 或的记录至少可以检测到明显的错误导致NXDOMAIN。然而，仍然会导致在寮屋地点造成的错误。 A记录解决的地址的另一步可能是检查25号端口在哪个地址上接受连接。

Allowing any name with an MX or A record at least detects obvious mistypings that result in NXDOMAIN. However it will still allow mistypings that end up at squatter sites. A further step for addresses resolved by A records might be to check where port 25 is accepting connections on that address.

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