votrechien - 9:35 pm on Jan 21, 2013 (gmt 0)
Legally (and arguably morally) there's nothing wrong with what you want to do. You have an existing relationship with the customer. However, we did the same thing (although it was closer to about 2 years worth of emails). We got kicked off of mailchimp pretty quick because customers reported us as a spammer (not true, but when a customer hasn't heard anything from your company in years their instinct is to click the 'spam' button).