What's most interesting to me about that is that they are willing to disclose that data to your email provider. Amazon, for example, is pretty cagey about what you've bought when sending emails, probably because they don't want Google to be able to use that information to target ads to you. (Not because they are Good and care about your privacy, but because they think they're going to beat Google at advertising. How's that going?)

So yeah, I don't get why they would do this. It gives their advertising competitors valuable data for free, and it pisses off customers by telling them that they're being tracked when they shop at Walgreens. Strange stuff.