Firstly the contact should be added to your accounting package - the contact will be added to Satago on the next data sync. Then, to send emails to the new contact, they must either be set to 'Primary Contact' or 'Escalation Contact'. Escalation Contacts are typically included in Reminders 3 to 5.
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The templates won't pull in a contact where Contact Type is set to 'None'.
Set/change the Primary Contact
Click into the customer record
Click the Contacts & Addresses tab
Click Edit next to the contact you wish to set as the Primary Contact
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Select the Pimary or Escalation Contact Type
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Click Update Contact
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