It holds more than 8m active, up-to-date and fully opted-in UK mail addresses.
The data comes from ISPs and data providers, including Wegener DM and The Mutual.net.
CACI cross-references it against the user's existing customer database and adds the matches.
The data meets legal requirements and is opted-in to receive third-or first party messages. Companies can only use it to contact existing customers.
"Customers are asked, either by the company they've opted in to or by us on behalf of our client, if they want to continue to opt-in, or receive messages from third-parties, or unsubscribe," Emma Crawford, head of marketing at CACI, said.
"They have the opportunity to opt out any time they like."
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .