Ubico lets you suppress emails and/or domains to prevent reaching out to current opportunities or existing customers.
Step 1: Navigate to your account settings.
Step 2: Add domains or emails to your workspace by entering them manually or copy-paste it to the text area. Additionally, you can drop a .csv file that contains the emails or domains. If you're putting more than one domain make sure to separate it with comma, space or new line.
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Once saved, these domains will not be contacted and will be used as a suppression list when searching and collecting data for your contacts.