PHP E-mail validation

From JumbaWiki

These sample scripts use a regular expression to check for a valid email address. You can define a constant for the regular expression like this:

 <?
 define('EMAIL_REGEX',"^([_a-z0-9-]+)(\.[_a-z0-9-]+)*@([a-z0-9-]+)(\.[a-z0-9-]+)*(\.[a-z]{2,4})$");
 ?>

The first function checks if the string passed to it is the correct format for an email address. It returns true if it looks valid, or false otherwise:

 <?
 function EmailIsValid($EmailAddr)
    {
    // Simple email check just looking at the string format
    if(eregi(EMAIL_REGEX, $EmailAddr))
        return true;
    else
        return false;
    }
 ?>

The next function performs the same test as above, and if the email address looks valid will try to contact the mail server before declaring the address ok.

 <?
 function EmailIsValid2($EmailAddr)
    {
    $valid = false;
    if (eregi(EMAIL_REGEX, $EmailAddr))
        {
        list($username,$domaintld) = split("@",$EmailAddr);
        if (getmxrr($domaintld,$mxrecords)) $valid = true;
        }
    else
        {
        $valid = false;
        }
    return $valid;
    }
 ?>

EmailIsValid2() uses the PHP built-in getmxrr() function. This function is not available on Windows servers, so to get around this you can define your own getmxrr() function:

 <?
 if(!function_exists('getmxrr'))
    { 
    // Replacement for getmxrr function on Windows server
    // "unable to fork" error usually means user IUSR_pcname needs read+execute perms on the exe
    function getmxrr($hostname, &$mxhosts)
        {
        $mxhosts = array();
        exec('%SYSTEMDIRECTORY%\\nslookup.exe -q=mx '.$hostname, $result_arr);
        foreach($result_arr as $line)
            {
            if (preg_match("/.*mail exchanger = (.*)/", $line, $matches))
                $mxhosts[] = $matches[1];
            }
        return( count($mxhosts) > 0 );
        }
    }
 ?>

See also

• PHP
• PHP Snippets
• Forms
• E-mail