If in a group there are more then 6 users (by default) then emails are send using cron. You can set cron interval in settings page of the plugin. Please remember, you need visitor in your website to run wordpress cron.
If in a group there are more then 6 users (by default) then emails are send using cron. You can set cron interval in settings page of the plugin. Please remember, you need visitor in your website to run wordpress cron.