Hello there.

Managing customer profiles in QuickBooks Online (QBO) is easy. I'm here to assist you with this matter.

In QuickBooks Online, the default setup allows only a single email address to be associated with each customer profile.

However, if you're referring to Sales forms, you can add multiple email addresses to the email field by separating them with a comma. (sample1@yahoo.com,sample2@yahoo.com)

If you have additional questions or need personalized assistance with managing your customers in QuickBooks Online, please feel free to reach out. I'm here to help whenever you need.