Why do customers unsubscribe from a mailing?
Remember that the top reasons people unsubscribe are related to frequency, content, and subscriber expectations. In addition to looking at the content and frequency of your emails, you'll also want to consider how your list changed over that particular period.
How do you implement an unsubscribe link in an email?
Click the Email tab. Select the Include unsubscribe link checkbox. To choose which phrase you want appear for your unsubscribe link, click Edit link text, then in the dialog box, select the radio button next to the link text that you want. Click Save.