• by Morgan Stewart , December 7, 2011

The most heated panel at this winter’s Email Insider Summit has been “When to Say Goodbye.” This group was asked to address the reality that more than half of most email subscriber files are inactive – meaning that subscribers have not opened or clicked on an email for some extended period of time. What should you do? Should you keep mailing, remove, attempt to reactivate?  And how do you determine who stays and who goes?

The predominant school of thought says that inactives should be removed periodically in order to maintain good deliverability. Fellow Email Insider Chad White wrote about this yesterday in his article “Email Inactivity Is Woefully Underaddressed.”

Alchemy Worx’ Dela Quist has been outspoken about his belief that this approach is draconian -- that tracking open and clicks are an insufficient measure of engagement and that the impact on deliverability is over-hyped. After all, a subject line reading “Black Friday – Doors Open at 6:00AM” is enough to get people engaged. They don’t need to open the email to get the information needed to take action. As such, marketers should not be quick to purge their “inactive” subscribers.

My problem with Chad’s approach is that it puts too much weight on the use of opens and clicks to measure engagement. He writes: “Subscriber inactivity should be defined by behavior in the inbox, which is all that ISPs care about when deciding whether to deliver email to a user. They don’t have visibility into whether that user is a loyal customer of yours or not, and don’t care… for the purposes of email engagement, keep a tight focus on email -- not business -- metrics.”

Wrong! If you can measure the activity of a email subscriber through means other than email,  then use them! ISPs do not expect you to have 100% engagement. Subscribers that see your email and then respond through search, a direct site visit, or in-store are not going to cause deliverability issues.

My problem with Dela’s approach is that it minimizes the impact inactive email addresses can have on deliverability. There are two scenarios where I have seen this become an issue:

1)   Inadequate list cleansing - Over time, inactive email addresses can be recycled by ISPs as a means of identifying mailers that aren’t cleaning their list appropriately. Not to worry, they will tell you before they do this through bounce codes that say the email address is no longer valid. So, if you are diligent about keeping your email list clean, if you send regularly and you have set up feedback loops and properly process ISP bounces, then email inactivity should not be an issue for you.

2)   Extremely low response rates – The industry average for opens is approximately 20% and the average click-through rate is approximately 4%. If your response rates are drastically lower than this (say 5% open rate and 1% click-through rate) then you may run into issues as the result of inactive email addresses even if you are cleaning your list appropriately. Then again, if you have response rates this low, you probably need to be doing more than simply purging inactive email addresses to get your email program back on track.

Deliverability can’t be the primary motivation for addressing the issue of inactive subscribers. It also can’t be dismissed. There are larger issues to take into consideration.

Assuming you are cleaning your list and your response rates are decent, the real question is the cost associated with sending email to these subscribers. True, the cost of sending email to one additional subscriber is nominal, but these costs add up quickly. If possible, segment these subscribers so you can track the revenue generated from your “inactive” file and compare that to the cost of sending email. At first, you may find this segment actually pays for itself. But over time as you move “re-engaged” subscribers back to your active file, it won’t. Once you have a list that is ROI negative, start looking for ways to invest that money more effectively.