This plugin will work best if you have the ability to run Cron Scripts on your web server.
The plugin needs to run specific functions at certain intervals to check for new messages for your mailing group(s), send messages on, check for bouncing messages to members, etc. The plugin is set to run these functions any time someone visits your website, as that helps the scripts in question be triggered into action.
However, if you have a low-traffic website, your mailing group messages will not be processed as regularly as you might like. This can be much improved if you have access to an online control panel, such as cPanel, where you can access the Cron Jobs, or Scheduled Tasks, and link to these scripts that are supplied with the plugin.
The instructions for this are included in the plugin’s Help section.