Labour has devised a cunning way to bolster the number of people on its party mailing list, under the guise of an online tool called 'find your baby number'.
The party's not denying it either, with deputy leader Annette King saying there's "nothing wrong with it".
The website celebrates Labour founding the public health system by revealing there have been more than 4 million babies delivered since 1938.
Users can enter their birth date to find out which number baby they would have been in the system.
But in order to find that out, they must enter their name and email.
It automatically signs users up to an email database and it's perfectly legitimate because the smallprint states: "The Labour Party and its elected representatives may contact you about issues we think you may be interested in or with campaign updates. You can unsubscribe at any time".
Ms King says there's nothing wrong with the process, and isn't shying away from the fact it's mining people's email addresses.
"Why shouldn't we do it? If people are willingly going to click on it, want to find out their baby number and give us their email, nothing wrong with that. In fact, let's celebrate that," she says.
"Don't use it if you don't want to, but if you do, we can send you information."
Her defence is that most other companies are doing it, saying "just about everything I go online to do these days has exactly that at the bottom of it".
Labour's not alone in its email farming tactics.
National did the same earlier this year when it invited people to send John Key a happy birthday message.
The only catch was that users had to use their email address, which added them to the party's mailing list.