Delivering e-mails today is becoming more of a challenge. ISPs are making it more difficult to get your message delivered, especially if you are trying to deliver a marketing message. Reputation is now becoming a major factor in e-mail deliverability. One of the key factors that ISPs look at is the “bounce rate” of your campaigns, so sending e-mail campaigns to a “dirty list” can create major delivery issues.

List fatigue is a common part of e-mail marketing, yet it is commonly overlooked. You probably spend time analyzing the e-mail metrics and web analytics generated by opens and clicks, monitoring unsubscribes and complaints, and watching for bounces or undelivered messages. All of these things are easy to track and report on and they provide valuable feedback you need to build better campaigns.

But what happens when nothing happens? If you aren’t paying attention to the subscribers who ignore or delete your messages you are missing out on a tremendous opportunity. And you’re putting your good reputation at risk.

Following is information about the common causes of list fatigue and what you can do to combat it, including the right and wrong ways to handle re-engagement campaigns and the pros and cons of removing subscribers from your list.

What is list fatigue?
List fatigue happens when your subscribers no longer respond to your messages. They don’t open or click on them, not even to unsubscribe. As the name suggests, list fatigue is caused by inactive and worn-out subscribers who simply ignore your e-mail campaigns over a period of time.

List fatigue is not easy to measure. Unlike other e-mail statistics you cannot gauge list fatigue by looking at the activity generated from an e-mail campaign. E-mail activity is tracked by certain occurrences – the e-mail bounces, the recipient opens or clicks on it, the subscriber forwards it to a friend, or the recipient unsubscribes. If the message is ignored or deleted without being opened, nothing is triggered so there is nothing to report. But, just because someone didn’t open your message doesn’t necessarily mean that they aren’t paying attention, which is why you can’t simply calculate list fatigue by monitoring the number of subscribers that haven’t opened a message over a number of months.

For example, many subscribers read messages in the preview pane without actually opening the e-mail. In order for a message to be tracked and counted as an opened message, something in the e-mail must trigger the response. This occurs when the recipient opens the message through a one-pixel image only if images are turned on either in the preview pane or full screen. However, if the recipient just reads your message without setting off the trigger by turning on the images it will not be counted. And while you can argue that someone who just reads your message with images turned off isn’t as interested in your offer as someone who clicks on the message and spends time on your web site, the fact that the e-mail is being read means the recipient is still active.

It’s the same for text-only messages. In order to be counted as an opened message, text-only messages must be clicked on to trigger the response. That automatically eliminates your recipients who only read your text messages without clicking on them.

Another difficulty when trying to measure list fatigue is that it must be measured over an arbitrary yet pre-determined amount of time. Figuring out how long to wait before deciding a subscriber is inactive is more of an educated guess than a science. Some best practices suggest that six months is enough time to tell, and for a lot of companies six months is the right number. However, if your organization sends e-mails five times a week, six months equals 130 messages, which could be too many. Or if you send quarterly, six months equals two messages, which might not be enough. And what if, like most retailers, you have a peak season that only occurs annually? Online florists see a spike leading up to Valentine’s Day, but they also receive orders for birthdays and well wishes throughout the year. If the florist removed inactive subscribers in August, six months after Valentine’s Day, it would miss out on orders for Thanksgiving Day centerpieces and every other special occasion throughout the year.

The only way to determine the right amount of time for your organization is to carefully monitor your metrics and analytics. Over time you will notice trends, and while they won’t be 100 percent accurate for every single subscriber, they will be relatively foolproof.

At this point you might be asking yourself if measuring your list fatigue to determine whom your inactive subscribers are is worth the trouble. After all, it’s possible for a subscriber to ignore your e-mails for two years and then suddenly decide to make a purchase. It is possible, but it isn’t probable, and when you’re dealing with metrics and analytics and trending, you must look for the practicalities in order to determine what the most likely outcome will be.

Peter Martin is the president of Cactus Sky Communications, Inc., one of the premier e-mail marketing agencies in the country. He is considered an e-Marketing expert and regularly speaks and trains for  National Auto Dealers Association and the National Independent Auto Dealers Association on both e-Marketing and special finance marketing.