在 PHP 中验证电子邮件

Question

我尝试了 PHP 正则表达式来验证电子邮件，例如

/^[_a-z0-9-]+(\.[_a-z0-9-])*@[a-z0-9-]+(\.[a-z0-9-])*(\.[a-z]{2,4})$/

。我知道这不是验证电子邮件的正确方法，因为

[email protected]

在我的正则表达式中也是正确的。

我需要枚举所有域名后缀吗？

我碰巧知道PHP中的filter_var函数可以验证电子邮件，但是

filter_var('[email protected]', FILTER_VALIDATE_EMAIL)

也是正确的。

什么是 PHP 源代码中的

FILTER_VALIDATE_EMAIL

理论？或者有人可以告诉我更好的方法来验证电子邮件吗？

非常感谢！

Answer 1

logic_filters.c

 中的函数 

php_filter_validate_email 用于此检查。

它根据以下正则表达式测试电子邮件

/^(?!(?:(?:\\x22?\\x5C[\\x00-\\x7E]\\x22?)|(?:\\x22?[^\\x5C\\x22]\\x22?)){255,})(?!(?:(?:\\x22?\\x5C[\\x00-\\x7E]\\x22?)|(?:\\x22?[^\\x5C\\x22]\\x22?)){65,}@)(?:(?:[\\x21\\x23-\\x27\\x2A\\x2B\\x2D\\x2F-\\x39\\x3D\\x3F\\x5E-\\x7E]+)|(?:\\x22(?:[\\x01-\\x08\\x0B\\x0C\\x0E-\\x1F\\x21\\x23-\\x5B\\x5D-\\x7F]|(?:\\x5C[\\x00-\\x7F]))*\\x22))(?:\\.(?:(?:[\\x21\\x23-\\x27\\x2A\\x2B\\x2D\\x2F-\\x39\\x3D\\x3F\\x5E-\\x7E]+)|(?:\\x22(?:[\\x01-\\x08\\x0B\\x0C\\x0E-\\x1F\\x21\\x23-\\x5B\\x5D-\\x7F]|(?:\\x5C[\\x00-\\x7F]))*\\x22)))*@(?:(?:(?!.*[^.]{64,})(?:(?:(?:xn--)?[a-z0-9]+(?:-+[a-z0-9]+)*\\.){1,126}){1,}(?:(?:[a-z][a-z0-9]*)|(?:(?:xn--)[a-z0-9]+))(?:-+[a-z0-9]+)*)|(?:\\[(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){7})|(?:(?!(?:.*[a-f0-9][:\\]]){7,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?)))|(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){5}:)|(?:(?!(?:.*[a-f0-9]:){5,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3}:)?)))?(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))(?:\\.(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))){3}))\\]))$/iD

 以及最大长度 320 个字符。

还有来自来源的评论：

/*
* The regex below is based on a regex by Michael Rushton.
* However, it is not identical. I changed it to only consider routeable
* addresses as valid. Michael's regex considers a@b a valid address
* which conflicts with section 2.3.5 of RFC 5321 which states that:
*
* Only resolvable, fully-qualified domain names (FQDNs) are permitted
* when domain names are used in SMTP. In other words, names that can
* be resolved to MX RRs or address (i.e., A or AAAA) RRs (as discussed
* in Section 5) are permitted, as are CNAME RRs whose targets can be
* resolved, in turn, to MX or address RRs. Local nicknames or
* unqualified names MUST NOT be used.
*
* This regex does not handle comments and folding whitespace. While
* this is technically valid in an email address, these parts aren't
* actually part of the address itself.
*
* Michael's regex carries this copyright:
*
* Copyright © Michael Rushton 2009-10
* http://squiloople.com/
* Feel free to use and redistribute this code. But please keep this copyright notice.
*
*/

这对于大多数现实世界的电子邮件来说已经足够了。有关更多详细信息，请查看此问题：

使用正则表达式验证电子邮件地址

Answer 2

使用下面的代码

 $email="[email protected]";
    if(filter_var($email, FILTER_VALIDATE_EMAIL)) {
        echo "This email is correct";

    }

希望这对您有帮助

Answer 3

if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
    return 'Valid Format';
}