Description:
------------
When we tried to sent 10 mails at the same time by using mail function(), Some mails were occurred SMTP 503 error such as 
Actual result portion.Please see the following "Actual result".


How to reproduce:
1)Launched your Web browser
2)Access send_mail.php script
   Repeat access send_mail.php by clicking reload button 
   on Web browser



Reproduce code:
---------------
<?php
define('MAIL_ADDER', 'ysuzuki@zend.co.jp');
define('MAIL_SEND_COUNT', 1);

header('Content-type: text/plain');

//Send Mail
for ($i = 0; $i <= MAIL_SEND_COUNT; $i++) {
    if (mail(MAIL_ADDER, "TEST MAIL $i", 'This is test Mail')) {
        echo "OK\n";
    } else {
        echo "BAT\n";
    }
}

?>

Expected result:
----------------
All send requested E-mail were successful by using mail() function even it was many requested from Web browser.

Actual result:
--------------
Error Message:
[18-Jan-2005 09:18:23] PHP Warning:  mail() [<a href='http://example.com/function.mail'>function.mail</a>]: Failed to connect to mailserver at "smtp.example.com" port 25, verify your "SMTP" and "smtp_port" setting in php.ini or use ini_set() in \\exampleserver\send_mail.php line xxx

[18-Jan-2005 09:18:23] PHP Warning:  mail() [<a href='http://example.com/function.mail'>function.mail</a>]: SMTP server response: 503 Sender already specified in \\exampleserver\send_mail.php on line xxx