The worldwide figure now stands at nearly three million with the firm adding 50,000 UK names in the week after Christmas.
Those signing up to receive the Leapfrog emails have to opt in and so far some 85 per cent of customers have done so. Once they sign up they receive information on product recommendations and retail offers.
"It’s because we know what they have bought and what they play with that we are able to make suggestions for what to go for next," said marketing manager David Lubliner.
"This is 100 per cent people who are the right age, like our products and want to hear from us,” added UK MD Chris Spalding (pictured).
"TV is a very shotgun approach so a lot is wasted on people who are not interested in the message. Our click through rates are about 20 per cent."
The system is also used to drive customers towards offers which Leapfrog creates in conjunction with its retail partners.
"When you have 4,000 to 5,000 people of that calibre being driven towards a retailer offer, that makes it a very powerful tool," added Spalding.