PHP FILTER_VALIDATE_EMAIL 无法正常工作

Question

我使用的是 PHP 5.3.10。这是代码：

<?php
$email = "test@example.c";
if (filter_var($email, FILTER_VALIDATE_EMAIL))
        echo "Email: ".$email." correct";
else
        echo "email not correct";
?>

它返回："Email: test@example.c 正确。

我认为只有一个字符的顶级域是不正确的（根据此列表，我不知道一个字符长度的 TLD：http://data.iana.org/TLD/tlds-alpha-by-domain.txt）。

那么，FILTER_VALIDATE_EMAIL 过滤器是否正常工作？

Answer 1

FILTER_VALIDATE_EMAIL只能告诉你地址格式是否正确。

考虑这些例子

// "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'

所以FILTER_VALIDATE_EMAIL 只擅长在完全错误的时候告诉你，而不是在正确的时候告诉你。

您将需要使用像Real Email 这样可以进行深入的电子邮件地址验证的服务。

// foo@gmail.com is invalid because gmail require more than 3 letters for the address.
var_export(file_get_contents("https://isitarealemail.com/api/email/validate?email=foo@gmail.com"));
'{"status":"invalid"}'

// foobar@gmail.com is valid
var_export(file_get_contents("https://isitarealemail.com/api/email/validate?email=foobar@gmail.com"));
'{"status":"valid"}'

更多信息请参见https://docs.isitarealemail.com/how-to-validate-email-addresses-in-php

Answer 2

验证电子邮件地址有点复杂。 看看这个列表：

有效的电子邮件地址

1. niceandsimple@example.com
2. very.common@example.com
3. a.little.lengthy.but.fine@dept.example.com
4. disposable.style.email.with+symbol@example.com
5. user@[IPv6:2001:db8:1ff::a0b:dbd0]
6. “非常不寻常”@example.com
7. "very.unusual.@.unusual.com"@example.com
8. "非常.(),:;[]".非常."非常@\ "非常".unusual"@strange.example.com
9. postbox@com（顶级域是有效的主机名）
10. admin@mailserver1（没有 TLD 的本地域名）
11. !#$%&'*+-/=?^_`{}|~@example.org
12. "()[]:,;@\"!#$%&'*+-/=?^_`{}| ~.a"@example.org
13. " "@example.org（引号之间的空格）
14. üñîçøðé​​@example.com（本地部分的 Unicode 字符）

电子邮件地址无效

1. Abc.example.com（@ 字符必须分隔本地和域 部分）
2. A@b@c@example.com（引号外只允许有一个@）
3. a"b(c)d,e:f;gi[j\k]l@example.com（没有特殊字符 在此本地部分中允许在引号之外）
4. just"not"right@example.com（引用的字符串必须用点分隔，或者 构成本地部分的唯一元素）
5. this is"not\allowed@example.com（空格、引号和反斜杠可能 仅存在于带引号的字符串中并以反斜杠开头）
6. this\ still"not\allowed@example.com（即使转义（前面 反斜杠）、空格、引号和反斜杠仍然必须是 包含在引号中）

来源http://en.wikipedia.org/wiki/Email_address

几乎所有的电子邮件验证实现都是“错误的”，但 php 实现很好用，因为它接受所有常见的电子邮件地址

更新：

发现于http://www.php.net/manual/en/filter.filters.validate.php

关于没有 .在域部分，源代码中的注释（在 ext/filter/logical_filters.c 中）证明了这种拒绝：

 * 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.

这是 Michael Rushton 的课程链接（链接已断开，请参阅下面的源代码） 支持 RFC 5321/5322

<?php
  /**
   * Squiloople Framework
   *
   * LICENSE: Feel free to use and redistribute this code.
   *
   * @author Michael Rushton <michael@squiloople.com>
   * @link http://squiloople.com/
   * @package Squiloople
   * @version 1.0
   * @copyright © 2012 Michael Rushton
   */
  /**
   * Email Address Validator
   *
   * Validate email addresses according to the relevant standards
   */
  final class EmailAddressValidator
  {
    // The RFC 5321 constant
    const RFC_5321 = 5321;
    // The RFC 5322 constant
    const RFC_5322 = 5322;
    /**
     * The email address
     *
     * @access private
     * @var string $_email_address
     */
    private $_email_address;
    /**
     * A quoted string local part is either allowed (true) or not (false)
     *
     * @access private
     * @var boolean $_quoted_string
     */
    private $_quoted_string = FALSE;
    /**
     * An obsolete local part is either allowed (true) or not (false)
     *
     * @access private
     * @var boolean $_obsolete
     */
    private $_obsolete = FALSE;
    /**
     * A basic domain name is either required (true) or not (false)
     *
     * @access private
     * @var boolean $_basic_domain_name
     */
    private $_basic_domain_name = TRUE;
    /**
     * A domain literal domain is either allowed (true) or not (false)
     *
     * @access private
     * @var boolean $_domain_literal
     */
    private $_domain_literal = FALSE;
   /**
     * Comments and folding white spaces are either allowed (true) or not (false)
     *
     * @access private
     * @var boolean $_cfws
     */
    private $_cfws = FALSE;
    /**
     * Set the email address and turn on the relevant standard if required
     *
     * @access public
     * @param string $email_address
     * @param null|integer $standard
     */
    public function __construct($email_address, $standard = NULL)
    {
      // Set the email address
      $this->_email_address = $email_address;
      // Set the relevant standard or throw an exception if an unknown is requested
      switch ($standard)
      {
        // Do nothing if no standard requested
        case NULL:
          break;
        // Otherwise if RFC 5321 requested
        case self::RFC_5321:
          $this->setStandard5321();
          break;
        // Otherwise if RFC 5322 requested
        case self::RFC_5322:
          $this->setStandard5322();
          break;
        // Otherwise throw an exception
        default:
          throw new Exception('Unknown RFC standard for email address validation.');
      }
    }
    /**
     * Call the constructor fluently
     *
     * @access public
     * @static
     * @param string $email_address
     * @param null|integer $standard
     * @return EmailAddressValidator
     */
    public static function setEmailAddress($email_address, $standard = NULL)
    {
      return new self($email_address, $standard);
    }
    /**
     * Validate the email address using a basic standard
     *
     * @access public
     * @return EmailAddressValidator
     */
    public function setStandardBasic()
    {
      // A quoted string local part is not allowed
      $this->_quoted_string = FALSE;
      // An obsolete local part is not allowed
      $this->_obsolete = FALSE;
      // A basic domain name is required
      $this->_basic_domain_name = TRUE;
      // A domain literal domain is not allowed
      $this->_domain_literal = FALSE;
      // Comments and folding white spaces are not allowed
      $this->_cfws = FALSE;
      // Return the EmailAddressValidator object
      return $this;
    }
    /**
     * Validate the email address using RFC 5321
     *
     * @access public
     * @return EmailAddressValidator
     */
    public function setStandard5321()
    {
      // A quoted string local part is allowed
      $this->_quoted_string = TRUE;
      // An obsolete local part is not allowed
      $this->_obsolete = FALSE;
      // Only a basic domain name is not required
      $this->_basic_domain_name = FALSE;
      // A domain literal domain is allowed
      $this->_domain_literal = TRUE;
      // Comments and folding white spaces are not allowed
      $this->_cfws = FALSE;
      // Return the EmailAddressValidator object
      return $this;
    }
    /**
     * Validate the email address using RFC 5322
     *
     * @access public
     * @return EmailAddressValidator
     */
    public function setStandard5322()
    {
      // A quoted string local part is disallowed
      $this->_quoted_string = FALSE;
      // An obsolete local part is allowed
      $this->_obsolete = TRUE;
      // Only a basic domain name is not required
      $this->_basic_domain_name = FALSE;
      // A domain literal domain is allowed
      $this->_domain_literal = TRUE;
      // Comments and folding white spaces are allowed
      $this->_cfws = TRUE;
      // Return the EmailAddressValidator object
      return $this;
    }
    /**
     * Either allow (true) or do not allow (false) a quoted string local part
     *
     * @access public
     * @param boolean $allow
     * @return EmailAddressValidator
     */
    public function setQuotedString($allow = TRUE)
    {
      // Either allow (true) or do not allow (false) a quoted string local part
      $this->_quoted_string = $allow;
      // Return the EmailAddressValidator object
      return $this;
    }
    /**
     * Either allow (true) or do not allow (false) an obsolete local part
     *
     * @access public
     * @param boolean $allow
     * @return EmailAddressValidator
     */
    public function setObsolete($allow = TRUE)
    {
      // Either allow (true) or do not allow (false) an obsolete local part
      $this->_obsolete = $allow;
      // Return the EmailAddressValidator object
      return $this;
    }
    /**
     * Either require (true) or do not require (false) a basic domain name
     *
     * @access public
     * @param boolean $allow
     * @return EmailAddressValidator
     */
    public function setBasicDomainName($allow = TRUE)
    {
      // Either require (true) or do not require (false) a basic domain name
      $this->_basic_domain_name = $allow;
      // Return the EmailAddressValidator object
      return $this;
    }
    /**
     * Either allow (true) or do not allow (false) a domain literal domain
     *
     * @access public
     * @param boolean $allow
     * @return EmailAddressValidator
     */
    public function setDomainLiteral($allow = TRUE)
    {
      // Either allow (true) or do not allow (false) a domain literal domain
      $this->_domain_literal = $allow;
      // Return the EmailAddressValidator object
      return $this;
    }
    /**
     * Either allow (true) or do not allow (false) comments and folding white spaces
     *
     * @access public
     * @param boolean $allow
     * @return EmailAddressValidator
     */
    public function setCFWS($allow = TRUE)
    {
      // Either allow (true) or do not allow (false) comments and folding white spaces
      $this->_cfws = $allow;
      // Return the EmailAddressValidator object
      return $this;
    }
    /**
     * Return the regular expression for a dot atom local part
     *
     * @access private
     * @return string
     */
    private function _getDotAtom()
    {
      return "([!#-'*+\/-9=?^-~-]+)(?>\.(?1))*";
    }
    /**
     * Return the regular expression for a quoted string local part
     *
     * @access private
     * @return string
     */
    private function _getQuotedString()
    {
      return '"(?>[ !#-\[\]-~]|\\\[ -~])*"';
    }
    /**
     * Return the regular expression for an obsolete local part
     *
     * @access private
     * @return string
     */
    private function _getObsolete()
    {
      return '([!#-\'*+\/-9=?^-~-]+|"(?>'
        . $this->_getFWS()
        . '(?>[\x01-\x08\x0B\x0C\x0E-!#-\[\]-\x7F]|\\\[\x00-\xFF]))*'
        . $this->_getFWS()
        . '")(?>'
        . $this->_getCFWS()
        . '\.'
        . $this->_getCFWS()
        . '(?1))*';
    }
    /**
     * Return the regular expression for a domain name domain
     *
     * @access private
     * @return string
     */
    private function _getDomainName()
    {
      // Return the basic domain name format if required
      if ($this->_basic_domain_name)
      {
        return '(?>' . $this->_getDomainNameLengthLimit()
          . '[a-z\d](?>[a-z\d-]*[a-z\d])?'
          . $this->_getCFWS()
          . '\.'
          . $this->_getCFWS()
          . '){1,126}[a-z]{2,6}';
      }
      // Otherwise return the full domain name format
      return $this->_getDomainNameLengthLimit()
        . '([a-z\d](?>[a-z\d-]*[a-z\d])?)(?>'
        . $this->_getCFWS()
        . '\.'
        . $this->_getDomainNameLengthLimit()
        . $this->_getCFWS()
        . '(?2)){0,126}';
    }
    /**
     * Return the regular expression for an IPv6 address
     *
     * @access private
     * @return string
     */
    private function _getIPv6()
    {
      return '([a-f\d]{1,4})(?>:(?3)){7}|(?!(?:.*[a-f\d][:\]]){8,})((?3)(?>:(?3)){0,6})?::(?4)?';
    }
    /**
     * Return the regular expression for an IPv4-mapped IPv6 address
     *
     * @access private
     * @return string
     */
    private function _getIPv4MappedIPv6()
    {
      return '(?3)(?>:(?3)){5}:|(?!(?:.*[a-f\d]:){6,})(?5)?::(?>((?3)(?>:(?3)){0,4}):)?';
    }
    /**
     * Return the regular expression for an IPv4 address
     *
     * @access private
     * @return string
     */
    private function _getIPv4()
    {
      return '(25[0-5]|2[0-4]\d|1\d{2}|[1-9]?\d)(?>\.(?6)){3}';
    }
    /**
     * Return the regular expression for a domain literal domain
     *
     * @access private
     * @return string
     */
    private function _getDomainLiteral()
    {
      return '\[(?:(?>IPv6:(?>'
        . $this->_getIPv6()
        . '))|(?>(?>IPv6:(?>'
        . $this->_getIPv4MappedIPv6()
        . '))?'
        . $this->_getIPv4()
        . '))\]';
    }
    /**
     * Return either the regular expression for folding white spaces or its backreference
     *
     * @access private
     * @param boolean $define
     * @return string
     */
    private function _getFWS($define = FALSE)
    {
      // Return the backreference if $define is set to FALSE otherwise return the regular expression
      if ($this->_cfws)
      {
        return !$define ? '(?P>fws)' : '(?<fws>(?>(?>(?>\x0D\x0A)?[\t ])+|(?>[\t ]*\x0D\x0A)?[\t ]+)?)';
      }
    }
    /**
     * Return the regular expression for comments
     *
     * @access private
     * @return string
     */
    private function _getComments()
    {
      return '(?<comment>\((?>'
        . $this->_getFWS()
        . '(?>[\x01-\x08\x0B\x0C\x0E-\'*-\[\]-\x7F]|\\\[\x00-\x7F]|(?P>comment)))*'
        . $this->_getFWS()
        . '\))';
    }
    /**
     * Return either the regular expression for comments and folding white spaces or its backreference
     *
     * @access private
     * @param boolean $define
     * @return string
     */
    private function _getCFWS($define = FALSE)
    {
      // Return the backreference if $define is set to FALSE
      if ($this->_cfws && !$define)
      {
        return '(?P>cfws)';
      }
      // Otherwise return the regular expression
      if ($this->_cfws)
      {
        return '(?<cfws>(?>(?>(?>'
          . $this->_getFWS(TRUE)
          . $this->_getComments()
          . ')+'
          . $this->_getFWS()
          . ')|'
          . $this->_getFWS()
          . ')?)';
      }
    }
    /**
     * Establish and return the valid format for the local part
     *
     * @access private
     * @return string
     */
    private function _getLocalPart()
    {
      // The local part may be obsolete if allowed
      if ($this->_obsolete)
      {
        return $this->_getObsolete();
      }
      // Otherwise the local part must be either a dot atom or a quoted string if the latter is allowed
      if ($this->_quoted_string)
      {
        return '(?>' . $this->_getDotAtom() . '|' . $this->_getQuotedString() . ')';
      }
      // Otherwise the local part must be a dot atom
      return $this->_getDotAtom();
    }
    /**
     * Establish and return the valid format for the domain
     *
     * @access private
     * @return string
     */
    private function _getDomain()
    {
      // The domain must be either a domain name or a domain literal if the latter is allowed
      if ($this->_domain_literal)
      {
        return '(?>' . $this->_getDomainName() . '|' . $this->_getDomainLiteral() . ')';
      }
      // Otherwise the domain must be a domain name
      return $this->_getDomainName();
    }
    /**
     * Return the email address length limit
     *
     * @access private
     * @return string
     */
    private function _getEmailAddressLengthLimit()
    {
      return '(?!(?>' . $this->_getCFWS() . '"?(?>\\\[ -~]|[^"])"?' . $this->_getCFWS() . '){255,})';
    }
    /**
     * Return the local part length limit
     *
     * @access private
     * @return string
     */
    private function _getLocalPartLengthLimit()
    {
      return '(?!(?>' . $this->_getCFWS() . '"?(?>\\\[ -~]|[^"])"?' . $this->_getCFWS() . '){65,}@)';
    }
    /**
     * Establish and return the domain name length limit
     *
     * @access private
     * @return string
     */
    private function _getDomainNameLengthLimit()
    {
      return '(?!' . $this->_getCFWS() . '[a-z\d-]{64,})';
    }
    /**
     * Check to see if the domain can be resolved to MX RRs
     *
     * @access private
     * @param array $domain
     * @return integer|boolean
     */
    private function _verifyDomain($domain)
    {
      // Return 0 if the domain cannot be resolved to MX RRs
      if (!checkdnsrr(end($domain), 'MX'))
      {
        return 0;
      }
      // Otherwise return true
      return TRUE;
    }
    /**
     * Perform the validation check on the email address's syntax and, if required, call _verifyDomain()
     *
     * @access public
     * @param boolean $verify
     * @return boolean|integer
     */
    public function isValid($verify = FALSE)
    {
      // Return false if the email address has an incorrect syntax
      if (!preg_match(
          '/^'
        . $this->_getEmailAddressLengthLimit()
        . $this->_getLocalPartLengthLimit()
        . $this->_getCFWS()
        . $this->_getLocalPart()
        . $this->_getCFWS()
        . '@'
        . $this->_getCFWS()
        . $this->_getDomain()
        . $this->_getCFWS(TRUE)
        . '$/isD'
        , $this->_email_address
      ))
      {
        return FALSE;
      }
      // Otherwise check to see if the domain can be resolved to MX RRs if required
      if ($verify)
      {
        return $this->_verifyDomain(explode('@', $this->_email_address));
      }
      // Otherwise return 1
      return 1;
    }
  }

2016 年编辑： 在 PHP 7.1 beta 中，我注意到以下内容：

• 根据 RFC 6531 实施电子邮件验证。（Leo Feyer，Anatol）。

参见第 3.3 节 https://www.rfc-editor.org/rfc/rfc6531#section-3.3

https://en.wikipedia.org/wiki/International_email

还有一些不错的额外示例

用户@例子.广告                 (Chinese, Unicode)
उपयोगकर्ता@उदाहरण.कॉम           (Hindi, Unicode)
юзер@екзампл.ком             (Ukrainian, Unicode)
θσερ@εχαμπλε.ψομ             (Greek, Unicode)
Dörte@Sörensen.example.com   (German, Unicode)

Answer 3

google 代码上有一个用于验证电子邮件地址的 PHP 类：

http://code.google.com/p/php-email-address-validation

你可以像这样使用它

include('EmailAddressValidator.php');
$validator = new EmailAddressValidator;
if ($validator->check_email_address('test@example.org')) { 
    // Email address is technically valid 
} else {
    // Email not valid
}

Answer 4

我选择使用：

<?php
$email =$argv[1];$result= is_valid_email($email); echo $result;
function is_valid_email($email) { return preg_match('/^(([^<>()[\]\\.,;:\s@"\']+(\.[^<>()[\]\\.,;:\s@"\']+)*)|("[^"\']+"))@((\[\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\])|(([a-zA-Z\d\-]+\.)+[a-zA-Z]{2,}))$/', $email); }
?>

在我的论坛软件中 https://github.com/neofutur/MyBestBB/blob/master/include/email.php#L39

但官方是这样的： http://www.ex-parrot.com/pdw/Mail-RFC822-Address.html （也更长）

Answer 5

FILTER_VALIDATE_EMAIL 不支持 PHP 5.2.14