You can make submissions to the Transact SMTP MTA only. Documents cannot contain multiple contacts.
You must send submissions to the Acoustic Campaign server address assigned to the IP address by Acoustic Campaign Support.
Example Find your organization's pod by going to high-level settings on to Acoustic Campaign. Therefore, your Transact Submission Address is transact-campaign-us-3.goacoustic.com.
Address: transact-campaign-us-[Pod number].goacoustic.com
Note: Security for Transact is handled with IP-level validation to ensure that no message can be sent from another source.