I'm having the exact same issue - Just wondering if a solution was ever provided?
PHP Fatal error: imap_headerinfo(): Address buffer overflow in /var/www/OSTicket/include/class.pop3.php on line 135
The function is:
function getHeaderInfo($mid) {
$headerinfo=imap_headerinfo($this->mbox,$mid);
$sender=$headerinfo->from;
//Parse what we need...
$header=array(
'from' =>array('name' =>@$sender->personal,'email' =>strtolower($sender->mailbox).'@'.$sender->host),
'subject'=>@$headerinfo->subject,);
return $header;
}