The “unsubscribe” button is a marketer’s biggest enemy, leading to lost readers and diminished opportunities. The goal with any email campaign is to retain as many readers as possible, with those numbers growing over time.

But as email management software firm Unroll.me points out, even the biggest companies aren’t immune to subscription drops. In its 2013 list of the most unsubscribed newsletters, Unroll.me ranked 1800 Flowers as the revolving door of email subscriptions, with an unsubscribe rate of 52.5 percent. Facebook (News - Alert) is the most common email subscription, with 70 percent of Unroll.me users receiving requested emails from the site.

Obviously, with Facebook the reason for high numbers is fairly clear. Facebook’s emails are generally sent to notify uses of new posts or messages on the system, while 1800 Flowers’ emails are usually marketing related. In fact, the vast majority of subscriptions on the “most unsubscribed” list are marketing oriented, including Pro Flowers, Expedia (News - Alert) and 1800 Contacts.

Businesses can learn something from Unroll.me’s list. To be as effective as possible, it’s crucial that marketers give readers a reason to not only leave their subscriptions intact, but open their emails when they arrive in their inboxes. Here are three great ways to ensure your e-newsletters are being read.

Inform and Enlighten

Avid newsletter readers are interested in content. If your newsletter simply exists to inform customers about your upcoming sales or your new line of products, you may be wasting your time and resources. Content should be informative and interesting, rather than 100 percent targeted toward your business. A florist could win views by creating a newsletter full of articles offering advice on romance or gardening, peppering in a coupon or occasional ad. Give your customers interesting content and they’ll not only keep reading, they may even look forward to your newsletter’s arrival in their inboxes.

Use Analytics

One of the best ways to determine whether your newsletter is resonating with customers is through analyzing and adjusting it on an ongoing basis. Split testing can be a great way to improve your results, providing information on everything from which subject lines get the best results to what time of day is best to send out your newsletter. Without testing, you may be sending your emails at a time when many of your customers are otherwise engaged, dramatically reducing the odd those emails will ever be opened.

Don’t Overdo It

According to marketing firm Chadwick Martin Bailey, the top reason customers unsubscribe is simply that they are receiving far too many emails from a particular sender. A powerful quarterly newsletter is far more likely to reach customers than a weekly or monthly newsletter with diluted content. The same goes for general marketing emails, which can begin taking a direct route to customers’ trash bins if sent too frequently.

Email newsletters are a great way to reach out to customers, offering content that will help them recognize you as an authority in your field. By measuring results and tweaking your strategies, you can ensure your newsletters are read and enjoyed by the majority of subscribers you sign up.