If you need to stop an automated campaign you can do so quickly and easily.
Head to the specific active automated campaign that you would like to stop.
Once you're viewing the campaign that you'd like to stop sending postcards. Click on the "Stop Campaign" button, and confirm your choice to stop the campaign.
Once you've completed this process your active campaign will no longer send postcards.
Other helpful resources
Here's how you can edit the design of an automated campaign