When you add a contact to Jetpack CRM, it has one main email address. AKA Mode adds an alias field, which allows you to input additional email addresses for that contact.
To enable this feature, go to Jetpack CRM Settings > General, and check the box for Use AKA Mode option.
If a contact has multiple email addresses, you can add them as aliases. You will need to add and save a contact first, then, you can find this Contact Aliases (AKA) section on the right side of the Edit Contact page.
If you get the error
This Alias is already in use by another contact., this means that the email address is already in use in another contact’s main address or added as an alias. You will need to change or remove the alias in another contact, or completely delete the other contact for you to add the email address.