Hi Christine,
Is it a cc email address for the registrant? If you go to Attendees > Attendee List > Click into the attendees name > Actions button > Edit Contact Information, scroll down and add the email address to the CC Email Address field and Save.
Also, do you just want to add it to their record for the future or do you also need to set it up so that the event emails go out to CC email addresses in addition to the main email address moving forward? If so, you can click into the email(s) > Advanced Settings tab > Edit > Send an additional copy of the email each time it is sent > Yes and check off CC Email Address and Save. You will need to repeat this for all emails you want to set this up for. Copying People on Registrant's Emails walks through this further!
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Julia Plymack
Senior Customer Success Manager
Cvent
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