Is Groupon leaking your email address to spammers? @groupon_UK

A while ago I set up a special email domain for using to track down who was leaking my email address to spammers.  From that point on every potentially dodgy website I sign up to has a unique email address that is only used on that site and nowhere else.  That means that I can check my spam email box and see who is leaking my email address.  Groupon – you are not the first company to email me and tell me that you’ve leaked my email address, but you are the first to leak my email address to a spammer (and I don’t recall them owning up to it but I could be wrong).
If you have ever signed up to a Groupon deal you know where some of your spam has come from (besides the rubbish they send you every day)