Instructions
Use Case: Send an email via Mass to a Person Account.
Issue: There is no field to point the contactfield parameter to.
Solution: Use PersonContactId for the contactfield parameter &contactfield=PersonContactId. If the Person Account is referenced in another object through a lookup (for example, if the object they are running from is an Opportunity, and want to send the email to the Person Account's contact) then you will need to use Account.PersonContactId instead (&contactfield=Account.PersonContactId)
