Jakob Nielsen's Alertbox, March 17, 2002:

Protecting the User's Mailbox

Summary:
Email is a powerful way to reach customers, but overdoing it is risky. Let users know up front that you'll respect their mailboxes. Otherwise, they won't give their email addresses, and you'll lose a unique channel for marketing and customer service.

Users are getting very protective of their mailboxes, and you must minimize the amount of email you send them. That said, there are two types of email that can enhance customer service and make people buy more:

Acknowledgment email, sent after a customer makes a purchase. This type of mail alleviates user fears about whether the system really has recorded their order. You can also send a second acknowledgment email when the order has shipped. This is an example of how the online world can be better than the real world: In the latter, it makes no sense to send a letter announcing that a FedEx package is on its way; online, the email will actually reach the customer before the package will and thus can do some good.
Announcements about events that customers want to be notified about. For example, a user might ask an airline to send email whenever the price of a ticket to Paris drops below $500. This is another "better than reality" feature: In the real world, it's infeasible for travel agents to continually watch for deals that few customers will actually pursue.

The key aspect of both examples is that the email is not spam. Rather, the email contains something of interest to a specific user that the user either asked for or expected to hear about. Also, both events above benefit from email's "push" nature: They occur at a specific point in time, and getting to the customer at that time is necessary if the customer is to benefit.

Even if a company plans to respect users' time and send only useful and appropriate email, people will still fear giving out their email addresses. However, you can entice users to disclose their email address by following these guidelines:

Offer a link to the privacy policy next to the box where users type in their email addresses.
- Or, even better: If the policy is ultra-short, just state it right there.
- If your legal department wrote the privacy policy, make sure it's edited by somebody who knows how to write for average readers.
Explain how your company will use the address (for example, only to notify the user of an order's status)
Have an obvious checkbox that lets users opt-in to receive additional information.
- Ensure that the checkbox is blank by default, so that users really do opt-in by checking it. Even if you violate this rule and require users to click to opt-out, the very fact that you provide a checkbox increases users' trust that you will respect their preferences.
- Explain what the additional mailings will entail and how often you'll send them.
If you offer a newsletter, link to a sample so that people can assess its quality and relevance.

Finally, every time you send users emails that are not direct follow-ups on a user request, always include clear instructions as to how they can unsubscribe.

Learn More

Our 544-page report from usability testing of email newsletters is available for download. It contains 165 design guidelines with best practices for increasing the usability of email newsletters.

Full-day tutorial on newsletter usability at the Usability Week 2009 conference in San Francisco.

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