Whether youโve got a green thumb or not, weโre all familiar with the idea of pruning: trimming back plants and trees to eradicate dead foliage and encourage attractive shapes and new growth.
And a hot topic that keeps popping up on my radar is email list pruning. The theory is essentially the same as in the gardenโselect cuts should encourage better results.
Itโs become a widespread belief that email list pruning is a necessity when it comes to maximizing program performance. But just as itโs possible to do more harm than good with some heavy-handed limb-chopping, slashing away at subscriber lists can be damaging to your bottom-line objectives.
How did email list pruning get so much traction in recent years?
The idea of email list pruning has its roots (har har) in the deliverability specialty.
When marketers find themselves in the thick of a deliverability crisis, a pretty standard tactic in the deliverability triage playbook is to suppress or delete subscribers who havenโt shown recent engagement while concurrently addressing other contributing factors (like eliminating any sketchy strategies that got you in hot water in the first place!).
The idea got legs. And over time, it evolved. Eventually, the idea of keeping lists extra-lean became mainstreamโeven when thereโs no sign of deliverability trouble.
Today, loads of marketers delete subscribers regularly without much thought. Does this sound like you? Iโd challenge you to reconsider.
Ask yourself why you want to trim lists.
Smaller lists mean youโre messaging fewer folks whoโve shown an interest in your brand. So why would you want to limit your reach? So far, Iโve only heard these three answers to justify email list pruning.
Which one is yours?
- Iโve got deliverability problems.
- Itโs a โbest practice.โ
- I want to save money.
1. Iโve got deliverability problems.
If youโre experiencing some serious inboxing challenges, then, by all means, you should investigate whether a lack of engagement is a factor. If it is, then absolutely consider aggressive suppression while you sort it out, ideally reserving subscriber deletion for when all else fails.
But donโt forgetโa lack of engagement isnโt actually solved by cutting subscribers from your list. If folks are opening and clicking so infrequently that youโve been banished to the spam folder, then youโre making some much bigger mistakes.
These might include crummy acquisition strategies, irrelevant and unpersonalized messaging, poor design and rendering, a lack of retention and re-engagement strategies, and any number of other factors that might leave subscribers feeling blah about your brand.
Are you digging deeper to sort out why youโre losing subscribersโ attention and making a plan to address those issues? Or simply dumping disappointed subscribers and calling it a day?
2. Itโs a โbest practice.โ
I often come across marketers looking for advice on how to explain to their higher-ups that email list pruning is a thing that MUST BE DONE. Theyโre struggling to make a case in favor of an ultra-lightweight list and need support articulating why it is a BEST PRACTICE. Because the boss just doesnโt seem to get it!
Sorry, friends, but thereโs a reason the boss challenges this thinking: because it defies logic.
If you caught my session at Iterableโs Activate 19 conference this year, then youโd know I have very, very strong feelings about BEST PRACTICES.
You can check out a recording of my sweary rant here: https://activate.iterable.com/sessions/best-practices-are-bullsht/ (Emphasis on sweary! Youโve been warned.)
The core message of that session is that โbest practicesโ arenโt always in your *best* interest.
There are two questions to ask yourself about any so-called best practice:
- Does this advance my business objective?
- Does this serve my audience?
Generally speaking, business objectives tend to involve metrics and goals such as revenue, retention, and customer lifetime value. Are you going to increase revenue, retention or LTV by sending to fewer people?
And if you arenโt seeing any signs of deliverability trouble, are you serving the folks who gave you permission to send email marketing by removing them from your lists? The same ones who said they want to hear from you?
Iโll concede that someone reading this article is able to answer those questions with a yesโand they have data that proves it. In that case, carry on, fine ladies and gents. There are always exceptions and you should believe your data.
But if you arenโt even looking beyond basic engagement data, then youโre not considering the money that youโre likely leaving on the table by ditching subscribers. And thatโs why the boss isnโt feeling it when you say you want to aggressively prune email lists.
I had the chance to work recently with a client that was deleting subscribers who hadnโt opened or clicked within 90 days. However, they abandoned this practice about five months before our meeting and we were able to see the before-and-after result. The marketer I was working with was bummed when we looked at month-over-month metrics. Open rates had dropped. Click rates had dropped.
โYeah, Iโm kinda worried about that,โ she said.
โIโm not,โ I replied, as I advanced to the terrifically nerdy pivot charts that showed open VOLUME was up tremendously. Click VOLUME was similarly growing. Unique purchases? UP. Revenue? IT WAS POPPIN!!!
So yeah, you wonโt max out open and click rates when you arenโt aggressively cutting subscribersโbut those arenโt the metrics that matter the most.
Ultimately, itโs all about dat shmoney, people. You shouldnโt be looking myopically at deliverability above all else just as you shouldnโt be looking exclusively at engagement above all else. Step back so you can see the forest for the trees (the wild, lush, unpruned forest, that is!).
3. I want to save money.
The third explanation Iโve heard to justify cutting subscriber lists is the cost of marketing to a larger list. Whether youโre paying your email service provider a CPM or a rate that is relevant to the size of your database, it certainly does cost more money to mail more subscribers.
But if you think that saving a buck or two per subscriber is a prudent financial decision for your brand, youโre thinking about the problem the wrong way. Allow me to explain.
This is a Tesla.

Pretty sweet ride, no? How would you like to own a Tesla? Sounds cool, right? If you really, REALLY wanted a Tesla, how would you go about getting one?
Would you start saving up by clipping 35-cent coupons for Charmin toilet tissue each month? How quickly would that pocket change turn into a car payment?
Now letโs consider that youโre spending $1.25 for the newspaper that contains the 35-cent coupon. That, folks, is where you start calculating the cost of acquiring those email addresses youโre so eager to delete. Suddenly youโre not saving anything at all. Youโre not even breaking even.
Wouldnโt a better strategy be to earn more money to achieve your goal? Say, a big promotion or new job? Wouldnโt a hefty boost in income get you behind the wheel of that Tesla faster than trying to scrimp and save a few extra dimes and nickels each month? How could you leverage your talents and skills and network to level-up your career?
The point here is that bigger lists produce bigger revenuesโwhen theyโre leveraged correctly. If youโre fixated on a coupon-clipping state of mind, then youโre missing the opportunity to maximize ROI. And in fact, you might be making short-sighted decisions that are a waste of money entirely.
Instead, consider what can you do with seemingly disengaged subscribers to revive them. Surely we should try a little fertilizer and sunshine before we start hacking away at the branch thatโs not blooming yet?
If you didnโt catch what Iโm getting at here, โfertilizerโ would be re-engagement strategies, improved personalization and relevance, and all-around surprise and delight.
Okay, Iโm sold. What now?
Itโs true that it probably doesnโt make much sense to treat those who arenโt showing email engagement the same way you treat those who are. As I mentioned, a re-engagement campaign should be your first line of defense in dealing with those who seem to have lost interest in your brand (while deleting is a last resort).
Still not getting traction? Consider less-frequent messaging for this segment, especially if inboxing is slipping. Thereโs not a one-size-fits-all formula for what that frequency should be, but a minimum of two to four messages a month will keep your brand present in the inbox and aid you in keeping lists healthy by capturing any hard bounces as they crop up.
And donโt forget, frequency should ramp back up when you do see engagement.
Still not getting the engagement youโre looking for after a re-engagement campaign and reduced frequency? Rinse and repeat, my friends. Itโs fine to re-launch re-engagement every three to six months when you donโt get the engagement youโre looking for in between.
Look at the big picture too. Just because youโre not getting engagement in the email channel doesnโt mean subscribers arenโt engaging with your brand at all. Perhaps theyโre on your website, on your app, in your brick-and-mortar location. Maybe theyโre following along on the socials or clicking on remarketing ads.
Talk to the stakeholders who own the other channelsโcan you share data or collaborate on strategies that might drive better engagement and retention?
Rememberโmore and more subscribers have taken an inventory mentality since the advent of the promotions tab. They know the messages are there when they want them.
And theyโll often let them pile up for ages with little more than the occasional skim. We email marketers did this to ourselvesโwe pounded away at inboxes with promotional messages for years and ISPs responded with the tabbed inbox.
Unread email doesnโt necessarily mean our messages are unwanted. Sometimes theyโre just tucked away until the right moment.
Also, thereโs a metric that we just donโt know how to quantify: inbox impressions. Thereโs no straightforward formula for calculating how many subscribers have skimmed your From Name and subject line and are keeping your brand top of mind for future reference. Maybe theyโre not engaging or buying today, but that doesnโt mean itโs not going to happen ever.
If theyโre not unsubscribing or complaining, and your deliverability isnโt tanking, should you assume they want off your list?
Now letโs take this analogy aaaaaaall the way home.
Sometimes you do need to lob off some fully dead branches, itโs true. But make a bad cut, and you might remove precious flower buds that will never see the sun (yeah, thatโs a revenue analogy, folks!).
The aim is to cultivate a rich, mature garden, and that takes timeโjust as it takes time to establish a long, loyal relationship with your customers. And those relationships are impossible to cultivate when we, the marketers, cut them short before thereโs a chance for them to grow and blossom.
If youโre interested in diving into the topic of frequency more deeply, check out the next Iterable webinar. Iโll be joined by Tasmin Singh from Iterableโs Customer Success team to talk about over- and under-sending email and mobile marketing channels. And be sure to check out our on-demand webinar on re-engagement campaigns.
You can also catch my insights on re-engagement strategy during my pre-con email workshop for the Digital Summit conferencesโIโll be presenting in Portland, Denver, Minneapolis, Chicago, D.C., Detroit, Boston, Raleigh, and Dallas. Hope to see you at one of them!
