In a bold move, CBS Sportsline cleans up their email lists by unsubscribing their readers. We also unsubscribed readers recently, and our list is healthier.

This is what their email said:

Dear CBS SportsLine.com Member, We would like to confirm that you still wish to receive THIS WEEK ON CBS SPORTSLINE.COM. This email newsletter is delivered to your inbox every week – bringing you updates and previews on the week’s expert analysis, video, Fantasy Sports advice and the hottest sports topics from CBS SportsLine.com writers. Please confirm your CBS SportsLine.com enrollment status by clicking on the confirmation button below. If we do not hear from you by April 30, 2007, we will remove you from this email list.

In today’s email environment, you shouldn’t care about the absolute number of subscribers you have. Instead, reader engagement, the quality of the relationship readers have with you, is what’s important.

Nobody expects subscribers to read every issue, but if they haven’t read a newsletter even once in three months, then assume they’re not interested or don’t have the time to invest in reading it. Make any other assumption and you risk the quality of your subscriber interaction. The last thing we want is for the newsletter to degrade into a perception of opt-in sp*m.

CBS Interactive is a client, so we’ll follow up with them to let you know more about their results from this email list cleanup.