On Netcore email API panel, you can make use of suppression feature available on Netcore email API panel to blacklist/suppress a user. In order to use the suppression option, you can follow the below steps,
1. Login to your Netcore email API panel, URL: https://email.netcorecloud.com
2. Go to suppression as shown under below image,
![](https://s3.amazonaws.com/cdn.freshdesk.com/data/helpdesk/attachments/production/17102168383/original/gR3NPzZAr-1YLN5OvaNeWNnh1BOpvrDtAg.png?1676370185)
3. Click on manage suppression as shown below,
![](https://s3.amazonaws.com/cdn.freshdesk.com/data/helpdesk/attachments/production/17102168391/original/Cvift7uxBqndWDyQlR-OBRjTMJm2_STtiQ.png?1676370197)
Once done, you get an option to add or remove an email address from suppression. Here you can either suppress an individual email address or upload a CSV of users to suppress them or to whitelist them on your Netcore email API account.
Please refer to the image below for more information,
![](https://s3.amazonaws.com/cdn.freshdesk.com/data/helpdesk/attachments/production/17102168430/original/wqtXfPeJUXPeX1_EpjCY0tLFpoPkp4FnoA.png?1676370257)
Hope this helps.