Hey Janos,
I am really sorry for the delay of this reply as it is a weekend for us here. It has everything to do with getting notified. Sending emails requires a communication between your site and the receiver's email server. This is how email works.
The script cannot be sending emails to subscribers when you reply to a user as this will give the user an impression that the system is slow (because it needs to send emails). Therefore, we queue the emails into a mail pool.
By doing this, there is 2 ways to dispatch emails out:
1. When you have the option "Send email on page load enabled", whenever a visitor visits EasyDiscuss, it tries to send the email (which is also bad)
2. Setup a cronjob so that everything runs on the background. Assuming that wget is stored in /usr/bin/wget on Siteground (I am not too sure what the exact path is, but you should check this with Siteground), this would be your cronjob command:
/usr/bin/wget -O /dev/null "http://www.simracinghub.com/index.php?option=com_easydiscuss&task=cron" >/dev/null 2>&1