If you have contacts that have subscribed to multiple groups, or people have just joined who you don't want to message just yet, you need to know how to exclude contacts. If you said someone the same message twice, or message them too soon after they opt-in, they can feel overwhelmed or spammed. It also wastes credits and money to send someone a message twice. So this feature is more for when there's a specific Campaign that shouldn't go out to everyone in a group.
How to Exclude Contacts
Go to the Campaigns tab.
Click on the Create New Campaign button.
Within Subscriber Filters is the option to upload a CSV file containing the contacts that you want to exclude. Click Add File and select the CSV file.
You can only attach a file that adheres to the following format.
The file should be populated with column-A containing 11-digit numbers. Please note that special characters are not required.