By this definition John sending an unexpected party invitation to his friend Dave is spam.
edit: I guess spam is by definition commercial email. Still, I think it's possible to have a business relationship with a company where it's acceptable for them to send an occasional email that you didn't specifically request.
edit: I guess spam is by definition commercial email. Still, I think it's possible to have a business relationship with a company where it's acceptable for them to send an occasional email that you didn't specifically request.