We break up email addresses into two categories: free webmail addresses and everything else. Anyone can have a free webmail address from Hotmail or Gmail, but not everyone has an address from Comcast or AT&T. Even fewer people have an email address from a company.
You have to be careful with your work address, but that's not so with free webmail addresses. You might give it to friends and family to get those precious forwarded jokes from your uncle. You might have certain addresses you use to make purchases online. In any case, list composition can tell you a lot about who your subscribers are.
It turns out Daily Deals send a lot more email to these free webmail ISPs than the average MailChimp subscriber. This tells us people tend to think of Daily Deals fondly. Then again, maybe people think of Daily Deals like utilitarian one-time services through which you purchase a robot vacuum. Either way, it's not something people typically receive at their work addresses.