System generated emails can be found in Project Configuration > System Email Templates.
This is a suggested template in html format, which can be previewed after entering into the editor window. To format the header / footer and colours you will need to customise the email design in App Appearance.
Registration complete simple template (copy and paste into the editor window)
IMPORTANT: You will have to manually add your email. To avoid missing any instances of these it is easiest to use a find and replace function on [email]
<p>Thank you for registering for our event.</p>
<p>You will receive updates in the lead up to the event as well as a link to download the summit app.</p>
<p>If you have any queries in the meantime, please email the summit team at <a href="mailto: [email]">[email]</a></p>