We found a record in Dynamics 365 that matches the record you're trying to create. When you track an email, if a contact ...

We found a record in Dynamics 365 that matches the record you're trying to create.
When you track an email, if a contact isn't found for that email address, a new one is automatically created. So if you recently tracked this particular email, a contact may have already been created. In the future, create the contact first, and then track the email.