If you are considering purchasing contacts data from a 3rd party supplier, please be aware that you should never agree to send over your existing contacts database to the 3rd party supplier for cross-referencing and detecting duplicates, under any circumstances.
By supplying a 3rd party with your contacts database you are in breach of data protection as you are effectively giving away your contacts database to a 3rd party who could then use this and sell this onto other businesses.
Please be cautious and if you have any questions please contact our Support Helpdesk for further information.