blocks|key|496710|text|我认为你最好使用PHP内置的filters+--在这个特殊的例子中：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|496711|当与FILTER_VALIDATE_EMAIL参数一起提供时，它可以返回true或false。|style|CODE|496712|entityMap|0|LINK|mutability|MUTABLE|url|http://php.net/manual/en/filter.filters.validate.php^0|E|7|0|0|2|L|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@$A|Q|B|R|1|S]]|C|$]]|$1|D|3|E|5|6|7|T|8|@$A|U|B|V|F|G]]|9|@]|C|$]]|$1|H|3|-4|5|6|7|W|8|@]|9|@]|C|$]]]|I|$J|$5|K|L|M|C|$N|O]]]]

I think you might be better off using PHP's inbuilt <a href="http://php.net/manual/en/filter.filters.validate.php" rel="noreferrer">filters</a> - in this particular case:

It can return a true or false when supplied with the <code>FILTER_VALIDATE_EMAIL</code> param.

blocks|key|279916|text|您可以使用filter_var来实现这一点。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|279917|<?php
+++function+validateEmail($email)+{
++++++return+filter_var($email,+FILTER_VALIDATE_EMAIL);
+++}
?>|code-block|syntax|javascript|279918|entityMap|0|LINK|mutability|MUTABLE|url|http://www.php.net/manual/en/function.filter-var.php^0|5|A|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

You can use <a href="http://www.php.net/manual/en/function.filter-var.php" rel="noreferrer">filter_var</a> for this.

<pre><code>&lt;?php
 function validateEmail($email) {
 return filter_var($email, FILTER_VALIDATE_EMAIL);
 }
?&gt;
</code></pre>

blocks|key|279976|text|如果你正在寻找一个允许不同的点，下划线和破折号的实际正则表达式，如下所示：[a-zA-z0-9.-]%2B\@[a-zA-z0-9.-]%2B.[a-zA-Z]%2B。这将允许像tom_anderson.1-neo@my-mail_matrix.com这样看起来相当愚蠢的电子邮件得到验证。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|279977|entityMap^0|11|14|2B|11|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

If you're just looking for an actual regex that allows for various dots, underscores and dashes, it as follows: <code>[a-zA-z0-9.-]+\@[a-zA-z0-9.-]+.[a-zA-Z]+</code>. That will allow a fairly stupid looking email like <code>tom_anderson.1-neo@my-mail_matrix.com</code> to be validated.

blocks|key|280021|text|在我的经验中，regex解决方案有太多的假阳性，而filter_var()解决方案有假阴性(特别是对于所有较新的TLDs)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|280022|相反，最好确保地址包含电子邮件地址的所有必需部分(用户、"@“符号和域)，然后验证域本身是否存在。|280023|无法确定(服务器端)外部域是否存在电子邮件用户。|280024|这是我在Utility类中创建的方法：|280025|public+static+function+validateEmail($email)
{
++++//+SET+INITIAL+RETURN+VARIABLES

++++++++$emailIsValid+=+FALSE;

++++//+MAKE+SURE+AN+EMPTY+STRING+WASN'T+PASSED

++++++++if+(!empty($email))
++++++++{
++++++++++++//+GET+EMAIL+PARTS

++++++++++++++++$domain+=+ltrim(stristr($email,+'@'),+'@')+.+'.';
++++++++++++++++$user+++=+stristr($email,+'@',+TRUE);

++++++++++++//+VALIDATE+EMAIL+ADDRESS

++++++++++++++++if
++++++++++++++++(
++++++++++++++++++++!empty($user)+&&
++++++++++++++++++++!empty($domain)+&&
++++++++++++++++++++checkdnsrr($domain)
++++++++++++++++)
++++++++++++++++{$emailIsValid+=+TRUE;}
++++++++}

++++//+RETURN+RESULT

++++++++return+$emailIsValid;
}|code-block|syntax|javascript|280026|entityMap|0|LINK|mutability|MUTABLE|url|https://en.wikipedia.org/wiki/Top-level_domain^0|7|5|P|C|1K|4|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@$9|13|A|14|1|15]]|E|$]]|$1|F|3|G|5|6|7|16|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|17|8|@]|D|@]|E|$]]|$1|J|3|K|5|6|7|18|8|@]|D|@]|E|$]]|$1|L|3|M|5|N|7|19|8|@]|D|@]|E|$O|P]]|$1|Q|3|-4|5|6|7|1A|8|@]|D|@]|E|$]]]|R|$S|$5|T|U|V|E|$W|X]]]]

In my experience, <code>regex</code> solutions have too many false positives and <code>filter_var()</code> solutions have false negatives (especially with all of the newer <a href="https://en.wikipedia.org/wiki/Top-level_domain" rel="noreferrer">TLDs</a>).

Instead, it's better to make sure the address has all of the required parts of an email address (user, "@" symbol, and domain), then verify that the domain itself exists.

There is no way to determine (server side) if an email user exists for an external domain.

This is a method I created in a Utility class:

<pre><code>public static function validateEmail($email)
{
 // SET INITIAL RETURN VARIABLES

 $emailIsValid = FALSE;

 // MAKE SURE AN EMPTY STRING WASN'T PASSED

 if (!empty($email))
 {
 // GET EMAIL PARTS

 $domain = ltrim(stristr($email, '@'), '@') . '.';
 $user = stristr($email, '@', TRUE);

 // VALIDATE EMAIL ADDRESS

 if
 (
 !empty($user) &amp;&amp;
 !empty($domain) &amp;&amp;
 checkdnsrr($domain)
 )
 {$emailIsValid = TRUE;}
 }

 // RETURN RESULT

 return $emailIsValid;
}
</code></pre>

blocks|key|496869|text|这不仅会验证您的电子邮件，还会对其进行清理，以防止意外字符：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|496870|$email++=+$_POST['email'];
$emailB+=+filter_var($email,+FILTER_SANITIZE_EMAIL);

if+(filter_var($emailB,+FILTER_VALIDATE_EMAIL)+===+false+%7C%7C
++++$emailB+!=+$email
)+{
++++echo+"This+email+adress+isn't+valid!";
++++exit(0);
}|code-block|syntax|javascript|496871|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This will not only validate your email, but also sanitize it for unexpected characters:

<pre><code>$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);
}
</code></pre>

blocks|key|280110|text|/(?![[:alnum:]]%7C@%7C-%7C_%7C\.)./|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|280111|现在，如果你在type=email中使用HTML5表单，那么你已经有了80%25的安全性，因为浏览器引擎有它们自己的验证器。为了补充它，将这个正则表达式添加到您的preg_match_all()中并对其求反：|unstyled|offset|length|style|CODE|280112|if+(!preg_match_all("/(?![[:alnum:]]%7C@%7C-%7C_%7C\.)./",$email))+{+..+}|280113|Find+the+regex+used+by+HTML5+forms+for+validation|280114|https://regex101.com/r/mPEKmy/1|280115|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/7786058/find-the-regex-used-by-html5-forms-for-validation|1^0|0|7|A|27|G|0|0|0|1D|0|0|0|V|1|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|10|8|@$G|11|H|12|I|J]|$G|13|H|14|I|J]]|9|@]|A|$]]|$1|K|3|L|5|6|7|15|8|@]|9|@]|A|$B|C]]|$1|M|3|N|5|F|7|16|8|@]|9|@$G|17|H|18|1|19]]|A|$]]|$1|O|3|P|5|F|7|1A|8|@]|9|@$G|1B|H|1C|1|1D]]|A|$]]|$1|Q|3|-4|5|F|7|1E|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]|Y|$5|T|U|V|A|$W|P]]]]

<pre><code>/(?![[:alnum:]]|@|-|_|\.)./
</code></pre>

Nowadays, if you use a HTML5 form with <code>type=email</code> then you're already by 80% safe since browser engines have their own validator. To complement it, add this regex to your <code>preg_match_all()</code> and negate it:

<pre><code>if (!preg_match_all("/(?![[:alnum:]]|@|-|_|\.)./",$email)) { .. }
</code></pre>

<a href="https://stackoverflow.com/questions/7786058/find-the-regex-used-by-html5-forms-for-validation">Find the regex used by HTML5 forms for validation</a> 
<a href="https://regex101.com/r/mPEKmy/1" rel="nofollow noreferrer">https://regex101.com/r/mPEKmy/1</a>

blocks|key|280160|text|在阅读了这里的答案后，我得到了以下结论：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|280161|public+static+function+isValidEmail(string+$email)+:+bool
{
++++if+(!filter_var($email,+FILTER_VALIDATE_EMAIL))+{
++++++++return+false;
++++}

++++//Get+host+name+from+email+and+check+if+it+is+valid
++++$email_host+=+array_slice(explode("@",+$email),+-1)[0];

++++//+Check+if+valid+IP+(v4+or+v6).+If+it+is+we+can't+do+a+DNS+lookup
++++if+(!filter_var($email_host,FILTER_VALIDATE_IP,+[
++++++++'flags'+=>+FILTER_FLAG_NO_PRIV_RANGE+%7C+FILTER_FLAG_NO_RES_RANGE,
++++]))+{
++++++++//Add+a+dot+to+the+end+of+the+host+name+to+make+a+fully+qualified+domain+name
++++++++//+and+get+last+array+element+because+an+escaped+@+is+allowed+in+the+local+part+(RFC+5322)
++++++++//+Then+convert+to+ascii+(http://us.php.net/manual/en/function.idn-to-ascii.php)
++++++++$email_host+=+idn_to_ascii($email_host.'.');

++++++++//Check+for+MX+pointers+in+DNS+(if+there+are+no+MX+pointers+the+domain+cannot+receive+emails)
++++++++if+(!checkdnsrr($email_host,+"MX"))+{
++++++++++++return+false;
++++++++}
++++}

++++return+true;
}|code-block|syntax|javascript|280162|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

After reading the answers here, this is what I ended up with:

<pre><code>public static function isValidEmail(string $email) : bool
{
 if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
 return false;
 }

 //Get host name from email and check if it is valid
 $email_host = array_slice(explode("@", $email), -1)[0];

 // Check if valid IP (v4 or v6). If it is we can't do a DNS lookup
 if (!filter_var($email_host,FILTER_VALIDATE_IP, [
 'flags' =&gt; FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE,
 ])) {
 //Add a dot to the end of the host name to make a fully qualified domain name
 // and get last array element because an escaped @ is allowed in the local part (RFC 5322)
 // Then convert to ascii (http://us.php.net/manual/en/function.idn-to-ascii.php)
 $email_host = idn_to_ascii($email_host.'.');

 //Check for MX pointers in DNS (if there are no MX pointers the domain cannot receive emails)
 if (!checkdnsrr($email_host, "MX")) {
 return false;
 }
 }

 return true;
}
</code></pre>

blocks|key|496991|text|使用以下代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|496992|//+Variable+to+check
$email+=+"john.doe@example.com";

//+Remove+all+illegal+characters+from+email
$email+=+filter_var($email,+FILTER_SANITIZE_EMAIL);


//+Validate+e-mail
if+(filter_var($email,+FILTER_VALIDATE_EMAIL))+{
++echo("Email+is+a+valid+email+address");
}|code-block|syntax|javascript|496993|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Use below code:
<pre class="lang-php prettyprint-override"><code>// Variable to check
$email = &quot;john.doe@example.com&quot;;

// Remove all illegal characters from email
$email = filter_var($email, FILTER_SANITIZE_EMAIL);


// Validate e-mail
if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
 echo(&quot;Email is a valid email address&quot;);
}
</code></pre>

blocks|key|497043|text|在FILTER_VALIDATE_EMAIL中有一个更好的正则表达式，但是任何正则表达式都可能产生不好的结果。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|497044|例如..|497045|//+"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'|code-block|syntax|javascript|497046|你可能想要考虑使用像Real+Email这样的应用程序接口，它可以进行深入的邮箱检查，以检查电子邮件是否真实。|497047|有点像..|497048|$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");
}|497049|entityMap|0|LINK|mutability|MUTABLE|url|https://www.php.net/manual/en/filter.filters.validate.php|1|https://isitarealemail.com/^0|1|L|0|0|0|0|A|A|1|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@$A|11|B|12|1|13]]|C|$]]|$1|D|3|E|5|6|7|14|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|15|8|@]|9|@]|C|$I|J]]|$1|K|3|L|5|6|7|16|8|@]|9|@$A|17|B|18|1|19]]|C|$]]|$1|M|3|N|5|6|7|1A|8|@]|9|@]|C|$]]|$1|O|3|P|5|H|7|1B|8|@]|9|@]|C|$I|J]]|$1|Q|3|-4|5|6|7|1C|8|@]|9|@]|C|$]]]|R|$S|$5|T|U|V|C|$W|X]]|Y|$5|T|U|V|C|$W|Z]]]]

theres is a better regex built in <a href="https://www.php.net/manual/en/filter.filters.validate.php" rel="nofollow noreferrer">FILTER_VALIDATE_EMAIL</a> but any regex can give bad results.
For example..
<pre class="lang-php prettyprint-override"><code>// &quot;not an email&quot; is invalid so its false.
php &gt; var_export(filter_var(&quot;not an email&quot;, FILTER_VALIDATE_EMAIL));
false
// &quot;foo@a.com&quot; looks like an email, so it passes even though its not real.
php &gt; var_export(filter_var(&quot;foo@a.com&quot;, FILTER_VALIDATE_EMAIL));
'foo@a.com'
// &quot;foo@gmail.com&quot; passes, gmail is a valid email server,
// but gmail require more than 3 letters for the address.
var_export(filter_var(&quot;foo@gmail.com&quot;, FILTER_VALIDATE_EMAIL));
'foo@gmail.com'
</code></pre>
You might want to consider using an API like <a href="https://isitarealemail.com" rel="nofollow noreferrer">Real Email</a> which can does in depth mailbox inspections to check if the email is real.
A bit like ..
<pre class="lang-php prettyprint-override"><code>$email = &quot;foo@bar.com&quot;;
$api_key = ???;

$request_context = stream_context_create(array(
 'http' =&gt; array(
 'header' =&gt; &quot;Authorization: Bearer &quot; . $api_key
 )
));

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

if (json_decode($result_json, true)['status'] == &quot;valid&quot;) {
 echo(&quot;email is valid&quot;);
} else if (json_decode($result_json, true)['status'] == &quot;invalid&quot;) {
 echo(&quot;email is invalid&quot;);
} else {
 echo(&quot;email was unknown&quot;);
}
</code></pre>

I have this function to validate an email addresses:

<pre><code>function validateEMAIL($EMAIL) {
 $v = "/[a-zA-Z0-9_-.+]+@[a-zA-Z0-9-]+.[a-zA-Z]+/";

 return (bool)preg_match($v, $EMAIL);
}
</code></pre>

Is this okay for checking if the email address is valid or not?

How to validate an email address in PHP

服务器

HTML5

我有以下功能来验证电子邮件地址：function validateEMAIL($EMAIL) {    $v = "/[a-zA-Z0-9_-.+]+@[a-zA-Z0-9-]+.[a-zA-Z]+/";    return (bool)preg_match($v, $EMAIL);}这可以检查电子邮件地址是否有效吗？

问如何在PHP中验证电子邮件地址
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