Too often, when marketers start focusing on growth, they're not asking, "How can I polish up my acquisition practices so my list attracts more qualified, engaged subscribers?" They're really saying, "How can I grow my list 50 percent this year?" 

That second focus can lead to tactics like one retailer's recent e-mail, which greeted prospective customers with this message: "Check it out! We think you'll have a lot in common, so we added you to (our) e-mail list." This practice is so wrong! 

You don't build a good mailing list by assuming your recipients will be interested, and you can't cover your actions by including an opt-out link. As with recovery or reactivation programs, you need an explicit opt-in. "No response" does not equal consent. 

Prechecked boxes on opt-in forms with fuzzy language and rented lists with dicey permission are other ways marketers build lists fast but open themselves to spam complaints, unsubscribes, and inactivity in the bargain.

Continue reading here: How to Improve Your Process for Acquiring E-mail Subscribers - ClickZ.