Description:
------------
When trying to receive a mail with a really long to-address field (e.g. Spam with 276 receivers) over pop3, PHP crashes. But it seems that it depends of the way I open the connection to the mailbox.

PHP crashes on long to-address mail if I use $mailbox = imap_open('{mail.myserver.net:110/pop3/novalidate-cert}INBOX', 'php@myserver.net', 'mydamnsecretpassword');, but everything works fine if I use $mailbox = imap_open('{mail.myserver.net:143}INBOX', 'php@myserver.net', 'mydamnsecretpassword');

Reproduce code:
---------------
//you'll need a mail with a lot of receivers for this test
$mailbox = imap_open('{mail.myserver.net:110/pop3/novalidate-cert}INBOX', 'php@myserver.net', 'mydamnsecretpassword');

$check = imap_check($mailbox);

for ($i=1; $i <= $check->Nmsgs; $i++)
{
    $uid = imap_uid($mailbox, $i);
    echo 'UID: '.$uid;
    $messageNumber = imap_msgno($mailbox, $uid);
    echo 'MessageNo: '.$messageNumber;
    $headerinfo = imap_headerinfo($mailbox, $messageNumber);
    [...]
}

Expected result:
----------------
$headerinfo contains an stdObject with headerinformation, like it does if it is a 'normal' mail

Actual result:
--------------
Crash with message 'This application has requested the Runtime to terminiate it in an unusual way. Please contact the application's support team for more information'