too many connections in email system in a2 hosting

I am now using laravel framework for web application. My problem is like as follows. when I am sending a message to all registered users, an exception error occurs saying there are too many connections. I read some answers in the internet and they told me to change "grep smtp_accept_max" in the service configuration. But I am using a2 hosting cpanel, and I can not find that configuration. Help me. Regards.

via Chebli Mohamed