Verifying the email address is the most challenging task in the web world. But on the other hand, it is necessary to verify the email address. Therefore, a valid email is beneficial to create your marketing profitable. But an invalid email upsurges your marking cost and effects on the email client’s reputation. Likewise, email validation is a valuable functionality on the web application. Before working with the email address, there is a need to verify and check whether the email is valid or not.

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Validate Email in PHP can be quickly done with the help of FILTER_VALIDATE_EMAIL filter. It will check if the format of the given email address is valid. But only this filter is not enough to check whether an email address exists. In this tutorial, we will show you how to check if an email address is real and exists using PHP.

In the PHP email verification script, we will validate an email address by checking MX DNS Record and domain. This script is handy to verify the user’s email address before sending an email or insert in the database. You can distinguish between real and invalid email address, and accept only the valid email address from the user.

PHP Email Verification Library

You can use the verify email class to check if an email address is valid and real using the SMTP protocol in PHP. You need to use one function of the VerifyEmail class to verify the email address in PHP.

check()

Validate the format of the email address.
Get MX records of the domain of the email address.
Connect to the SMTP server by the MX records.
Based on the response code:
- Check the given recipient email address is valid.
- Check the user of the email’s domain exists.
- Check the delivery of the message.

<?php 
/** 
 * Class to validate the email address 
 * 
 * @author CodexWorld.com <[email protected]> 
 * @copyright Copyright (c) 2018, CodexWorld.com
 * @url https://www.codexworld.com
 */ 
class VerifyEmail { 

    protected $stream = false; 

    /** 
     * SMTP port number 
     * @var int 
     */ 
    protected $port = 25; 

    /** 
     * Email address for request 
     * @var string 
     */ 
    protected $from = '[email protected]'; 

    /** 
     * The connection timeout, in seconds. 
     * @var int 
     */ 
    protected $max_connection_timeout = 30; 

    /** 
     * Timeout value on stream, in seconds. 
     * @var int 
     */ 
    protected $stream_timeout = 5; 

    /** 
     * Wait timeout on stream, in seconds. 
     * * 0 - not wait 
     * @var int 
     */ 
    protected $stream_timeout_wait = 0; 

    /** 
     * Whether to throw exceptions for errors. 
     * @type boolean 
     * @access protected 
     */ 
    protected $exceptions = false; 

    /** 
     * The number of errors encountered. 
     * @type integer 
     * @access protected 
     */ 
    protected $error_count = 0; 

    /** 
     * class debug output mode. 
     * @type boolean 
     */ 
    public $Debug = false; 

    /** 
     * How to handle debug output. 
     * Options: 
     * * `echo` Output plain-text as-is, appropriate for CLI 
     * * `html` Output escaped, line breaks converted to `<br>`, appropriate for browser output 
     * * `log` Output to error log as configured in php.ini 
     * @type string 
     */ 
    public $Debugoutput = 'echo'; 

    /** 
     * SMTP RFC standard line ending. 
     */ 
    const CRLF = "\r\n"; 

    /** 
     * Holds the most recent error message. 
     * @type string 
     */ 
    public $ErrorInfo = ''; 

    /** 
     * Constructor. 
     * @param boolean $exceptions Should we throw external exceptions? 
     */ 
    public function __construct($exceptions = false) { 
        $this->exceptions = (boolean) $exceptions; 
    } 

    /** 
     * Set email address for SMTP request 
     * @param string $email Email address 
     */ 
    public function setEmailFrom($email) { 
        if (!self::validate($email)) { 
            $this->set_error('Invalid address : ' . $email); 
            $this->edebug($this->ErrorInfo); 
            if ($this->exceptions) { 
                throw new verifyEmailException($this->ErrorInfo); 
            } 
        } 
        $this->from = $email; 
    } 

    /** 
     * Set connection timeout, in seconds. 
     * @param int $seconds 
     */ 
    public function setConnectionTimeout($seconds) { 
        if ($seconds > 0) { 
            $this->max_connection_timeout = (int) $seconds; 
        } 
    } 

    /** 
     * Sets the timeout value on stream, expressed in the seconds 
     * @param int $seconds 
     */ 
    public function setStreamTimeout($seconds) { 
        if ($seconds > 0) { 
            $this->stream_timeout = (int) $seconds; 
        } 
    } 

    public function setStreamTimeoutWait($seconds) { 
        if ($seconds >= 0) { 
            $this->stream_timeout_wait = (int) $seconds; 
        } 
    } 

    /** 
     * Validate email address. 
     * @param string $email 
     * @return boolean True if valid. 
     */ 
    public static function validate($email) { 
        return (boolean) filter_var($email, FILTER_VALIDATE_EMAIL); 
    } 

    /** 
     * Get array of MX records for host. Sort by weight information. 
     * @param string $hostname The Internet host name. 
     * @return array Array of the MX records found. 
     */ 
    public function getMXrecords($hostname) { 
        $mxhosts = array(); 
        $mxweights = array(); 
        if (getmxrr($hostname, $mxhosts, $mxweights) === FALSE) { 
            $this->set_error('MX records not found or an error occurred'); 
            $this->edebug($this->ErrorInfo); 
        } else { 
            array_multisort($mxweights, $mxhosts); 
        } 
        /** 
         * Add A-record as last chance (e.g. if no MX record is there). 
         * Thanks Nicht Lieb. 
         * @link http://www.faqs.org/rfcs/rfc2821.html RFC 2821 - Simple Mail Transfer Protocol 
         */ 
        if (empty($mxhosts)) { 
            $mxhosts[] = $hostname; 
        } 
        return $mxhosts; 
    } 

    /** 
     * Parses input string to array(0=>user, 1=>domain) 
     * @param string $email 
     * @param boolean $only_domain 
     * @return string|array 
     * @access private 
     */ 
    public static function parse_email($email, $only_domain = TRUE) { 
        sscanf($email, "%[^@]@%s", $user, $domain); 
        return ($only_domain) ? $domain : array($user, $domain); 
    } 

    /** 
     * Add an error message to the error container. 
     * @access protected 
     * @param string $msg 
     * @return void 
     */ 
    protected function set_error($msg) { 
        $this->error_count++; 
        $this->ErrorInfo = $msg; 
    } 

    /** 
     * Check if an error occurred. 
     * @access public 
     * @return boolean True if an error did occur. 
     */ 
    public function isError() { 
        return ($this->error_count > 0); 
    } 

    /** 
     * Output debugging info 
     * Only generates output if debug output is enabled 
     * @see verifyEmail::$Debugoutput 
     * @see verifyEmail::$Debug 
     * @param string $str 
     */ 
    protected function edebug($str) { 
        if (!$this->Debug) { 
            return; 
        } 
        switch ($this->Debugoutput) { 
            case 'log': 
                //Don't output, just log 
                error_log($str); 
                break; 
            case 'html': 
                //Cleans up output a bit for a better looking, HTML-safe output 
                echo htmlentities( 
                        preg_replace('/[\r\n]+/', '', $str), ENT_QUOTES, 'UTF-8' 
                ) 
                . "<br>\n"; 
                break; 
            case 'echo': 
            default: 
                //Normalize line breaks 
                $str = preg_replace('/(\r\n|\r|\n)/ms', "\n", $str); 
                echo gmdate('Y-m-d H:i:s') . "\t" . str_replace( 
                        "\n", "\n \t ", trim($str) 
                ) . "\n"; 
        } 
    } 

    /** 
     * Validate email
     * @param string $email Email address 
     * @return boolean True if the valid email also exist 
     */ 
    public function check($email) { 
        $result = FALSE; 

        if (!self::validate($email)) { 
            $this->set_error("{$email} incorrect e-mail"); 
            $this->edebug($this->ErrorInfo); 
            if ($this->exceptions) { 
                throw new verifyEmailException($this->ErrorInfo); 
            } 
            return FALSE; 
        } 
        $this->error_count = 0; // Reset errors 
        $this->stream = FALSE; 

        $mxs = $this->getMXrecords(self::parse_email($email)); 
        $timeout = ceil($this->max_connection_timeout / count($mxs)); 
        foreach ($mxs as $host) { 
            /** 
             * suppress error output from stream socket client... 
             * Thanks Michael. 
             */ 
            $this->stream = @stream_socket_client("tcp://" . $host . ":" . $this->port, $errno, $errstr, $timeout); 
            if ($this->stream === FALSE) { 
                if ($errno == 0) { 
                    $this->set_error("Problem initializing the socket"); 
                    $this->edebug($this->ErrorInfo); 
                    if ($this->exceptions) { 
                        throw new verifyEmailException($this->ErrorInfo); 
                    } 
                    return FALSE; 
                } else { 
                    $this->edebug($host . ":" . $errstr); 
                } 
            } else { 
                stream_set_timeout($this->stream, $this->stream_timeout); 
                stream_set_blocking($this->stream, 1); 

                if ($this->_streamCode($this->_streamResponse()) == '220') { 
                    $this->edebug("Connection success {$host}"); 
                    break; 
                } else { 
                    fclose($this->stream); 
                    $this->stream = FALSE; 
                } 
            } 
        } 

        if ($this->stream === FALSE) { 
            $this->set_error("All connection fails"); 
            $this->edebug($this->ErrorInfo); 
            if ($this->exceptions) { 
                throw new verifyEmailException($this->ErrorInfo); 
            } 
            return FALSE; 
        } 

        $this->_streamQuery("HELO " . self::parse_email($this->from)); 
        $this->_streamResponse(); 
        $this->_streamQuery("MAIL FROM: <{$this->from}>"); 
        $this->_streamResponse(); 
        $this->_streamQuery("RCPT TO: <{$email}>"); 
        $code = $this->_streamCode($this->_streamResponse()); 
        $this->_streamResponse(); 
        $this->_streamQuery("RSET"); 
        $this->_streamResponse();
        $code2 = $this->_streamCode($this->_streamResponse()); 
        $this->_streamQuery("QUIT"); 
        fclose($this->stream); 
        
        $code = !empty($code2)?$code2:$code;
        switch ($code) { 
            case '250': 
            /** 
             * http://www.ietf.org/rfc/rfc0821.txt 
             * 250 Requested mail action okay, completed 
             * email address was accepted 
             */ 
            case '450': 
            case '451': 
            case '452': 
                /** 
                 * http://www.ietf.org/rfc/rfc0821.txt 
                 * 450 Requested action not taken: the remote mail server 
                 * does not want to accept mail from your server for 
                 * some reason (IP address, blacklisting, etc..) 
                 * Thanks Nicht Lieb. 
                 * 451 Requested action aborted: local error in processing 
                 * 452 Requested action not taken: insufficient system storage 
                 * email address was greylisted (or some temporary error occured on the MTA) 
                 * i believe that e-mail exists 
                 */ 
                return TRUE;
            case '550':
                return FALSE; 
            default : 
                return FALSE; 
        } 
    } 

    /** 
     * writes the contents of string to the file stream pointed to by handle 
     * If an error occurs, returns FALSE. 
     * @access protected 
     * @param string $string The string that is to be written 
     * @return string Returns a result code, as an integer. 
     */ 
    protected function _streamQuery($query) { 
        $this->edebug($query); 
        return stream_socket_sendto($this->stream, $query . self::CRLF); 
    } 

    /** 
     * Reads all the line long the answer and analyze it. 
     * If an error occurs, returns FALSE 
     * @access protected 
     * @return string Response 
     */ 
    protected function _streamResponse($timed = 0) { 
        $reply = stream_get_line($this->stream, 1); 
        $status = stream_get_meta_data($this->stream); 

        if (!empty($status['timed_out'])) { 
            $this->edebug("Timed out while waiting for data! (timeout {$this->stream_timeout} seconds)"); 
        } 

        if ($reply === FALSE && $status['timed_out'] && $timed < $this->stream_timeout_wait) { 
            return $this->_streamResponse($timed + $this->stream_timeout); 
        } 


        if ($reply !== FALSE && $status['unread_bytes'] > 0) { 
            $reply .= stream_get_line($this->stream, $status['unread_bytes'], self::CRLF); 
        } 
        $this->edebug($reply); 
        return $reply; 
    } 

    /** 
     * Get Response code from Response 
     * @param string $str 
     * @return string 
     */ 
    protected function _streamCode($str) { 
        preg_match('/^(?<code>[0-9]{3})(\s|-)(.*)$/ims', $str, $matches); 
        $code = isset($matches['code']) ? $matches['code'] : false; 
        return $code; 
    } 

} 

/** 
 * verifyEmail exception handler 
 */ 
class verifyEmailException extends Exception { 

    /** 
     * Prettify error message output 
     * @return string 
     */ 
    public function errorMessage() {
        $errorMsg = $this->getMessage(); 
        return $errorMsg; 
    } 

} 

?>

Usage

You can use it to validate the email address using PHP.

Initialize the library class using VerifyEmail().
Set the timeout, debug, and sender email address.
Call check() function and pass the email address which you want to validate.
- Returns TRUE if the given email address is valid and real. Also, it indicates that the domain of this email exists, and the user is correct.
- Returns FALSE if the given email address is invalid and not exists.
If the check() function returns FALSE, you can check the email with validate() service to check if the email format is valid, but the user not exists on the domain.

<?php

// Include library file
require_once 'VerifyEmail.class.php'; 

// Initialize library class
$mail = new VerifyEmail();

// Set the timeout value on stream
$mail->setStreamTimeoutWait(20);

// Set debug output mode
$mail->Debug= TRUE; 
$mail->Debugoutput= 'html'; 

// Set email address for SMTP request
$mail->setEmailFrom('[email protected]');

// Email to check
$email = '[email protected]'; 

// Check if email is valid and exist
if($mail->check($email)){ 
    echo 'Email &lt;'.$email.'&gt; is exist!'; 
}elseif(verifyEmail::validate($email)){ 
    echo 'Email &lt;'.$email.'&gt; is valid, but not exist!'; 
}else{ 
    echo 'Email &lt;'.$email.'&gt; is not valid and not exist!'; 
} 

?>

Also, read our previous blog- jQuery UI Autocomplete with Images and Custom HTML in PHP

Tags: PHP Verify Email Address