电子邮件地址中有没有资本？ [英] Did capitals ever matter in email addresses?

问题描述

我的爸爸说资本对于电子邮件地址过去很重要（几年前），但不再这样了。我相当肯定他们从来没有这样做，因为涉及DNS / MX更改的东西不会改变。特别是在线上找不到记录。

解决方案

我们来看看这个：

电子邮件地址的域部分需要符合RFC 1034，因此（一直以来）不区分大小写：

http://www.ietf.org/rfc/rfc1034.txt

电子邮件地址的本地部分由接收邮件服务器处理，因此理论上是否对其进行敏感的处理取决于该服务器。一些邮件服务器选择强加规则，除了RFC 5322（例如Gmail忽略点）或放松（例如，亚洲的大多数邮件服务器允许在开头和结尾处扩展标点符号）。

邮件服务器理论上可以理解（同时打破RFC 5322）实现区分大小写。

那就是说，我不知道有一个或一个曾经这样做。

My dad says capitals used to matter (years ago) for email addresses but don't anymore. I'm fairly sure they never did because something like that involving DNS/MX changes would not change. Especially with no easy to find record online.

解决方案

Let's look at this in pieces:

The domain part of the email address needs to conform to RFC 1034 and is thus (and has always been) case insensitive:

http://www.ietf.org/rfc/rfc1034.txt

The local part of the email address is handled by the receiving mail server and thus whether or not it is treated case-sensitively in theory depends on that server. Some mail servers choose to impose rules in addition to RFC 5322 (e.g. Gmail ignoring dots) or relax them (e.g. most mail servers in Asia allowing extended punctuation at beginnings and endings of addresses).

A mail server MAY in theory (while breaking RFC 5322) implement case sensitivity.

That said, I am not aware of a single one that does or has ever done so.

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