CACI has also partnered with The Great UK Survey, which is providing additional email addresses to CACI's database. The survey firm conducts demographic, lifestyle and consumer purchasing data surveys online.
Aaron O'Sullivan, managing director at The Great UK Survey, said: "We have strict processes in place to ensure consumer data isn't used in an unethical or irrelevant manner.
"eAppend is fully compliant with all data protection legislation, so we are more than happy for email addresses collected via our surveys to be incorporated into this database."
Nick Moffett, managing consultant at CACI, said that eAppend had consistently helped numerous well known brands to implement effective email marketing strategies.
He said: "This is in recognition of the fact that eAppend is one of the most comprehensive sources of accurate email addresses currently available. It is our aim to ensure this remains the case by signing up additional content partners as and when appropriate."