电邮地址是否区分大小写？ [英] Are email addresses case sensitive?
问题描述
我已经看到，标准的第一部分电子邮件是区分大小写的，但是我试图发送电子邮件到 name@example.com Name@example.com 和 NAME@example.com - 它已经到达每一种情况。
I've read that by standard first part of e-mail is case sensitive, however I've tried to send e-mail to name@example.com, Name@example.com and NAME@example.com - it has arrived in each case.
邮件服务器如何处理用户名？是否可能错过案件，该邮件将不会传递？使用完全相同的字母大小写真的非常重要吗，如同在注册时写的电子邮件地址一样？
How do mail servers handles usernames? Is it possible to miss with case and that message wouldn't be delivered? Is it really very important to use exactly same letter case, as was written while registering when giving your e-mail address?
推荐答案
从RFC 5321，section-2.3.11：
From RFC 5321, section-2.3.11:
标准邮箱命名约定定义为
local-part @域;当代使用允许比简单的用户名更广泛的
应用程序。因此，当中间主机试图通过修改
来优化传输时，由于
长的问题历史，本地部分必须是
解释和分配语义，只能由主机指定
域名地址的一部分。
The standard mailbox naming convention is defined to be "local-part@domain"; contemporary usage permits a much broader set of applications than simple "user names". Consequently, and due to a long history of problems when intermediate hosts have attempted to optimize transport by modifying them, the local-part MUST be interpreted and assigned semantics only by the host specified in the domain part of the address.
所以是的，@之前的部分可以区分大小写，因为它完全在主机系统的控制之下。实际上，没有广泛使用的邮件系统根据案例区分不同的地址。
So yes, the part before the "@" could be case-sensitive, since it is entirely under the control of the host system. In practice though, no widely used mail systems distinguish different addresses based on case.
然而，@符号之后的部分是域，根据RFC 1035，第3.1节，
The part after the @ sign however is the domain and according to RFC 1035, section 3.1,
名称服务器和解析器必须以不区分大小写的方式比较[domains]
"Name servers and resolvers must compare [domains] in a case-insensitive manner"
简而言之，您可以安全地将电子邮件地址视为不区分大小写。
In short, you are safe to treat email addresses as case-insensitive.
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