What this means? If it's just the email list, probably just an increase in the spam I'll get (and you'll get if you were subscribed to their email lists). According to the emails I received it was just email addresses. Here's an excerpt from the email I got from Walgreens:
On March 30th, we were informed by Epsilon, a company we use to send emails to our customers, that files containing the email addresses of some customers were accessed without authorization.The rest of the email was just a reminder of basic email security, not giving out your credit card info, ignoring scams, etc.
We have been assured by Epsilon that the only information that was obtained was your email address. No other personally identifiable information was at risk because such data is not contained in Epsilon's email system.