All you have to do to avoid having the SMTP server create a new campaign every time you send out emails is to add the appropriate guide on the headers of the email.
What you are looking for is the following guide:
- campaign_guid: your_campaign_id :
This is the ID of your campaign, whose statistics will be recorded for every transactional email sent through our SMTP service.
If you don't use the above guide on the header of the email a new campaign will be created based on the subject of the email you sent out.
Make sure to check the other guide which is available for you to use when sending out campaigns via our SMTP service.