verification test of a list

before submitting a list to constant-contact I want to see if the emails are actual emails

not just in the correct format
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rgb192Asked:
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Ray PaseurCommented:
http://www.experts-exchange.com/Web_Development/Web_Languages-Standards/PHP/A_3939-Registration-and-Email-Confirmation-in-PHP.html

That is the only way that I know of to completely verify that an email exists and gets to a human being.  The code snippet will tell you whether the email is well-formed and routable.

<?php // RAY_email_validation.php
error_reporting(E_ALL);


// A FUNCTION TO TEST FOR A VALID EMAIL ADDRESS, RETURN TRUE OR FALSE
// SEE MAN PAGE: http://php.net/manual/en/intro.filter.php
function check_valid_email($email, $rout=TRUE)
{
    // LIST OF BLOCKED DOMAINS
    $bogus = array
    ( '@unknown.com'
    , '@example.com'
    , '@gooseball.org'
    )
    ;

    // IF PHP 5.2 OR ABOVE, WE CAN USE THE FILTER
    if (strnatcmp(phpversion(),'5.2') >= 0)
    {
        if(filter_var($email, FILTER_VALIDATE_EMAIL) === FALSE) return FALSE;
    }

    // IF LOWER-LEVEL PHP, WE CAN CONSTRUCT A REGULAR EXPRESSION
    else
    {
        $regex
        = '/'                        // START REGEX DELIMITER
        . '^'                        // START STRING
        . '[A-Z0-9_-]'               // AN EMAIL - SOME CHARACTER(S)
        . '[A-Z0-9._-]*'             // AN EMAIL - SOME CHARACTER(S) PERMITS DOT
        . '@'                        // A SINGLE AT-SIGN
        . '([A-Z0-9][A-Z0-9-]*\.)+'  // A DOMAIN NAME PERMITS DOT, ENDS DOT
        . '[A-Z\.]'                  // A TOP-LEVEL DOMAIN PERMITS DOT
        . '{2,6}'                    // TLD LENGTH >= 2 AND =< 6
        . '$'                        // ENDOF STRING
        . '/'                        // ENDOF REGEX DELIMITER
        . 'i'                        // CASE INSENSITIVE
        ;
        // TEST THE STRING FORMAT
        if (!preg_match($regex, $email)) return FALSE;
    }

    // TEST TO SEE IF THE DOMAIN IS IN OUR BLOCKED LIST
    foreach ($bogus as $badguy)
    {
        if (stripos($email, $badguy)) return FALSE;
    }

    // FILTER_VAR OR PREG_MATCH DOES NOT TEST IF THE DOMAIN IS ROUTABLE
    if ($rout)
    {
        $domain = explode('@', $email);

        // MAN PAGE: http://php.net/manual/en/function.checkdnsrr.php
        if ( checkdnsrr($domain[1], "MX") || checkdnsrr($domain[1], "A") ) return TRUE;

        // EMAIL IS NOT ROUTABLE
        return FALSE;
    }
    return TRUE;
}



// DEMONSTRATE THE FUNCTION IN ACTION
$e = NULL;
if (!empty($_GET["e"]))
{
    $e = $_GET["e"];
    if (check_valid_email($e))
    {
        echo "<br/>VALID: $e \n";
    }
    else
    {
        echo "<br/>BOGUS: $e \n";
    }
}


// END OF PROCESSING - CREATE THE FORM USING HEREDOC NOTATION
$form = <<<ENDFORM
<form>
TEST A STRING FOR A VALID EMAIL ADDRESS:
<input name="e" value="$e" />
<input type="submit" />
</form>
ENDFORM;

echo $form;

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HTH, ~Ray

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rgb192Author Commented:
thanks
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