To manage the automatic sending rules click on the "More" button on the right side of your screen. You will then be able to select "Automatic sending rules".

An automatic sending rule is the condition for which an email will be sent out to a guest automatically depending on their participant to an event.

For example if you want your confirmed guest to receive an automatic message when he/she changes his/her registration form  you will only have to check “Guest updates his registration”.