Microsoft has been sneaking some holiday gifts into its email newsletters recently. Reddit posters noticed that if you click the red trees in a holiday promotional email from Microsoft then you’ll be sent to a separate site that provides a free $10 gift card. The software giant has even been hiding these gift cards in emails as far back as Black Friday, where you could click on a blue squirrel to receive a $10 discount.

It appears only a limited number of gift cards were available, as the promotion on existing emails has finished. Microsoft could still email out more mysterious messages in the coming days before the holidays, so be prepared to hunt through any messages from the company for hidden clues.