您可以为此使用filter_var。

<?php
   function validateEmail($email) {
      return filter_var($email, FILTER_VALIDATE_EMAIL);
   }
?>

在FILTER_VALIDATE_EMAIL中有一个更好的正则表达式，但任何正则表达式都可能给出糟糕的结果。

例如. .

// "not an email" is invalid so its false.
php > var_export(filter_var("not an email", FILTER_VALIDATE_EMAIL));
false
// "foo@a.com" looks like an email, so it passes even though its not real.
php > var_export(filter_var("foo@a.com", FILTER_VALIDATE_EMAIL));
'foo@a.com'
// "foo@gmail.com" passes, gmail is a valid email server,
//  but gmail require more than 3 letters for the address.
var_export(filter_var("foo@gmail.com", FILTER_VALIDATE_EMAIL));
'foo@gmail.com'

你可能会考虑使用像Real Email这样的API，它可以进行深入的邮箱检查，以检查电子邮件是否真实。

有点像…

$email = "foo@bar.com";
$api_key = ???;

$request_context = stream_context_create(array(
    'http' => array(
        'header'  => "Authorization: Bearer " . $api_key
    )
));

$result_json = file_get_contents("https://isitarealemail.com/api/email/validate?email=" . $email, false, $request_context);

if (json_decode($result_json, true)['status'] == "valid") {
    echo("email is valid");
} else if (json_decode($result_json, true)['status'] == "invalid") {
    echo("email is invalid");
} else {
  echo("email was unknown");
}

我准备了一个检查电子邮件有效性的函数:

function isValidEmail($email)
{
    $re = '/([\w\-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([\w-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)/m';
    preg_match_all($re, $email, $matches, PREG_SET_ORDER, 0);
    if(count($matches) > 0) return $matches[0][0] === $email;
    return false;
}

FILTER_VALIDATE_EMAIL的问题是，它甚至认为无效的电子邮件是有效的。

以下是例子:

if(isValidEmail("foo@gmail.com")) echo "valid";
if(!isValidEmail("fo^o@gmail.com")) echo "invalid";

有三个rfc奠定了“Internet消息格式”的基础。

RFC 822 RFC 2822(取代RFC 822) RFC 5322(取代RFC 2822)

然而，RFC 5322以最专业的方式定义了电子邮件id及其命名结构。这更适合于为一个互联网标准奠定基础，这个标准足够自由，可以允许所有的用例，也足够保守，可以用某种形式主义来约束它。

然而，来自软件开发人员社区的电子邮件验证需求，有以下需求——

避免不必要的垃圾邮件发送者 确保用户不会因疏忽而出错 以确保电子邮件ID属于实际输入它的人

They are not exactly interested in implementing a technically all-encompassing definition that allows all the forms (IP addresses, including port IDs and all) of e-mail id. The solution suitable for their use-case is expected to solely ensure that all the legitimate e-mail holders should be able to get through. The definition of "legitimate" differs vastly from technical stand-point (RFC 5322 way) to usability stand-point(this solution). The usability aspect of the validation aims to ensure that all the e-mail IDs validated by the validation mechanism belong to actual people, using them for their communication purposes. This, thus introduces another angle to the validation process, ensuring an actually "in-use" e-mail ID, a requirement for which RFC-5322 definition is clearly not sufficient.

因此，在实际的基础上，实际的要求归结为这一点

以确保一些非常基本的验证检查 确保输入的电子邮件正在使用

第二个需求通常包括向输入的电子邮件ID发送标准响应，并根据响应机制中描述的操作对用户进行身份验证。这是用于确保验证“使用中”电子邮件ID的第二个需求的最广泛使用的机制。这确实涉及到从后端服务器实现的往返，并且不是一个直接的单屏幕实现，但是，我们不能放弃这一点。

The first requirement, stems from the need that the developers do not want totally "non e-mail like" strings to pass as an e-mail. This typically involves blanks, strings without "@" sign or without a domain name. Given the punycode representations of the domain names, if one needs to enable domain validation, they need to engage in full-fledged implementation that ensures a valid domain name. Thus, given the basic nature of requirement in this regard, validating for "<something>@<something>.<something>" is the only apt way of satisfying the requirement.

一个典型的正则表达式可以满足这个要求: ^ ^ @ \ [s] + @ ^ @ \ [s] + [^ @ \ s]。+ $ 上面的正则表达式遵循大多数编程语言都广泛遵循的标准Perl正则表达式标准。验证语句是: <除空格和“@”符号>之外的任何东西@<除空格和“@”符号>之外的任何东西。<除空格、@符号和点>之外的任何东西

对于那些想要更深入地了解更相关的实现的人，他们可以遵循以下验证方法。 <电子邮件本地部分>@<域名>

对于<电子邮件本地部分> -遵循“通用验收指导小组”- UASG-026的指导方针 对于<域名>，您可以使用标准库遵循任何域验证方法，这取决于您的编程语言。关于该主题的最新研究，请参考文档UASG-018A。

那些有兴趣了解在实施国际化电子邮件解决方案时可能遇到的整体流程、挑战和问题的人，也可以通过以下rfc:

RFC 6530(国际化电子邮件概述和框架) RFC 6531(国际化电子邮件的SMTP扩展名) RFC 6532(国际化邮件头) RFC 6533(国际化交付状态和处置通知) RFC 6855 (IMAP支持UTF-8) RFC 6856(邮局协议版本3 (POP3)支持UTF-8) RFC 6857(国际化电子邮件消息的发送后消息降级) RFC 6858(简化POP和IMAP降级国际化电子邮件)。

这不仅可以验证你的邮件，还可以过滤掉意想不到的字符:

$email  = $_POST['email'];
$emailB = filter_var($email, FILTER_SANITIZE_EMAIL);

if (filter_var($emailB, FILTER_VALIDATE_EMAIL) === false ||
    $emailB != $email
) {
    echo "This email adress isn't valid!";
    exit(0);
}

在关于电子邮件验证的“顶级问题”中回答了这个问题https://stackoverflow.com/a/41129750/1848217

For me the right way for checking emails is: Check that symbol @ exists, and before and after it there are some non-@ symbols: /^[^@]+@[^@]+$/ Try to send an email to this address with some "activation code". When the user "activated" his email address, we will see that all is right. Of course, you can show some warning or tooltip in front-end when user typed "strange" email to help him to avoid common mistakes, like no dot in domain part or spaces in name without quoting and so on. But you must accept the address "hello@world" if user really want it. Also, you must remember that email address standard was and can evolute, so you can't just type some "standard-valid" regexp once and for all times. And you must remember that some concrete internet servers can fail some details of common standard and in fact work with own "modified standard".

所以，只要检查@，提示用户在前端和发送验证电子邮件在给定的地址。