sending mail from Contact person email id

Hi Guruu2019s

In Customer master, Under General Data tab, there is a Contact person which is having Email id.

The requirement is that to send PDF attached invoice automatically to the contact person (customer)from (Table : KNVK).

If the value for the email is available for that contact person, then only the invoice mail(attached PDF invoice) has to trigger to the customer. If not, mail must not trigger to the customer.

(Already code has been written for triggering of the mail to the customers and it is working fine).

Which fields I have to take into consideration for creating an access sequence. So that I can create a condition record in VV31.

Ex : Customer,Department, Contact person Function, Partner Function, Medium, Language.

Please correct me