To blacklist/whistelist email account in Cpanel go to Spam filters -> Show additional configuration. Then depending on the preferred option, choose “Edit Spam Whitelist Settings” or “Edit Spam Blacklist Settings”. Click on “+ Add A New item”, put the email account there and then click on Update.
To blacklist/whitelist a wildcard email account, use such command, with replacing the relevant domain name.
Updated 8 days ago