User Emails Failing


I'm sending emails via I'm trying to send an email to my 353 users. After sending 100 emails I get this error:

Server Error

fwrite(): SSL operation failed with code 1. OpenSSL Error messages: error:140D00CF:SSL routines:SSL_write:protocol is shutdown

    fwrite() in Zend/Mail/Protocol/Abstract.php at line 324
    Zend_Mail_Protocol_Abstract->_send() in Zend/Mail/Protocol/Smtp.php at line 385
    Zend_Mail_Protocol_Smtp->quit() in Zend/Mail/Transport/Smtp.php at line 144
    Zend_Mail_Transport_Smtp->__destruct() in XenForo/FrontController.php at line 310
    XenForo_ControllerAdmin_User->actionEmailSend() in XenForo/FrontController.php at line 310
    XenForo_FrontController->dispatch() in XenForo/FrontController.php at line 132
    XenForo_FrontController->run() in /home/soc_lsucs/ at line 13
I can see the emails are being sent via google mail. I've tried using TLS and SSL, both end with the same result.

Server is running Ubuntu 10.04.03 LTS with latest php 5 packages.