You've been going through your settings and have spotted the field Support Email Address under Event Setup > Settings > Event Basics. We recommend that this be filled out for every event. You want to know where attendees can find this - no problem.
It will appear in the footer of your public event site through the 'Contact us' hyperlink.
If you don't fill out this field, the 'Contact' us link in the footer will lead to your custom email address if you have one set up. If you don't have either filled out, it will lead to your Event Organizer email address (the one your HeySummit subscription is under).
The support email address you choose will also automatically be shown in the Payment Receipt email. If you don't fill out this field, your custom email address will be shown. If neither is filled out, your Event Organizer email address will be shown.
However, if someone replies to one of your event emails, they will be sending a message to your custom email address rather than your event support email. If you don't have a custom email address filled out, it will be forwarded to your Event Organizer HeySummit account email.