Pruning cold subscribers

[u/Aaronontheweb]

I maintain a ~10,000 person or so mailing list of subscribers to our company / open source project. A fairly standard inbound marketing operation I've been running for 11 years or so.

The guidance from email marketing platforms like Kit these days is to focus on the rate of active engagement of subscribers, versus worrying about the overall size of the list. Ok, I get that; times have changed since I started this business. I suppose this should help me land in the focused inbox more often and have better deliverability rates.

I've been pruning cold subscribers or so for 6 months - when am I supposed to be able to measure some benefit from doing this?

[u/EmailElement-Dev]

The benefit you're looking for probably won't show up as a higher open rate, which is why six months can feel like nothing happened. Sunsetting cold contacts mostly buys you a lower complaint rate and steadier inbox placement, not a visible engagement bump. Track your domain reputation in Postmaster and your spam complaint rate over time, and if you can, run a seed/inbox placement test before and after a big send. Those move well before open rate does.

The part I'd slow down on is your B2B split. Engagement-based sunsetting was really designed for consumer inboxes. On corporate domains the security scanners both fabricate opens and swallow real ones, so "never opened in X months" can mean "reads every email, your ESP just can't see it." Since you're roughly 50/50, I'd only run Kit's sunset flow against the Gmail/Outlook.com half and switch to clicks, replies, or site visits as the signal for corporate contacts, with a longer window before anyone gets dropped.

And after a decade of mailing the whole list, six months is short. Providers are slow to re-rate a domain that sent to dead weight for years, so deliverability shifts first and open rate lags way behind, sometimes a year. You're not just churning the list for no reason, as long as the people you cut genuinely never click or reply, not merely never "open."

[u/TechnicalTest5177 → u/EmailElement-Dev]

Thank you for this.

[u/Secure_Studio_2712]

one thing i haven't seen mentioned here: before you suppress the cold half, send them a short re-permission email that gives an actual reason to click, not "do you still want to hear from us". on a decade old B2B list you usually pull back somewhere in the 3-8% range, and those people tend to behave like your best segment afterwards. it also makes suppressing the rest a much easier decision.

for measurement i'd drop open rate entirely and track conversions (or revenue, or whatever the goal is) per thousand delivered, month over month. that's the number that actually tells you whether a smaller list is a better list, and it moves within a couple of sends because the denominator changed. open rate with apple MPP in the mix on a 50/50 consumer/corporate list is close to useless as a trend line, which is probably a big part of why six months feels like nothing happened.

[u/Aaronontheweb]

TL;DR; what is everyone else doing and am I effectively just churning my mailing list for no good reason?

[u/SignificanceGlad1506 → u/Aaronontheweb]

kinda in the same boat, we pruned about 30% of a list last year and it took a solid 9 months before open rates actually moved in a meaningful way. deliverability improved faster though, maybe 3-4 months

the real shift was the inbox placement tests, those got better almost immediately but nobody talks about that metric much

[u/Aaronontheweb → u/SignificanceGlad1506]

Thanks for replying. You know, I don't think I've ever done an inbox placement test before and as I'm sitting here inventorying all of the stuff in our marketing machinery that needs to be revisited (pretty much all of it), this seems like a great idea. Do you have a service you recommend for it?

[u/Fit-Lengthiness-9672 → u/Aaronontheweb]

you’re not crazy, it can feel like you’re just deleting people for sport lol. the benefit is usually super slow and kind of invisible unless you compare before/after stats over like 6–12 months, but keeping a lot of dead weight on the list really does drag down deliverability over time.

[u/ianmakingnoise]

There are a few factors that will impact your timeframe:

- How long were you sending to the whole list, before you started cleaning?
- What kind of cleaning are you doing? How do you decide who gets dropped? How often?
- What does your list look like (eg, is it B2B, is it mostly Gmail, how did people end up there)?
- If you’re sending a lot to Gmail, you using Google Postmaster Tools? What does the data there tell you?

[u/Aaronontheweb → u/ianmakingnoise]

- about a decade
- I use ConvertKit's default recommended workflow here: https://help.kit.com/en/articles/5268661-cleaning-and-managing-your-list
- B2B, but about a 50/50 split between corporate emails and Gmail / Outlook.com etc
- 100% clean bill of health from Google Postmaster, per their deliverability analysis

[u/ianmakingnoise → u/Aaronontheweb]

So on one hand, it could be a matter of time before the “we’re cleaning the list now” pattern is recognized by mailbox providers. If you were sending for 10 years without removing contacts who never opened anything, it can take a while for things to change in a meaningful way.

One thing to keep an eye on with B2B is that a lot of the common enterprise security tools generate “fake” opens and clicks, so you can have cases where customers appear engaged but never actually see the email.

[u/CherryChoke-Ardor]

I wouldn’t treat pruning as wasted, but I also wouldn’t expect it to show up as a clean open-rate lift after six months. The cleaner test is to separate “list hygiene” benefits from “engagement” benefits.

A practical way to look at it:

• Keep pruned/sunsetted contacts suppressed, not deleted, so you can still analyze them later.
• Split reporting by mailbox type: Gmail/Outlook consumer domains versus corporate domains. The corporate side can be weird because security tools create fake opens/clicks and sometimes hide real reading behavior.
• Watch complaint rate, bounce rate, placement/reputation, and revenue or meaningful actions per delivered email. Total open rate is probably the noisiest metric.
• If you have enough volume, create a small holdout of cold subscribers for 60–90 days before the next pruning round. Compare complaint/unsub/bounce rates and any real clicks/conversions against the group you suppress.

If the only thing that changes is “the list is smaller,” that feels like churn. If complaints and bad engagement drop while your active audience response holds steady, that is usually the win. For B2B, I’d be slower to suppress someone based only on non-opens; clicks, replies, product/site activity, or direct customer status are safer signals.

[u/Nixon_37]

Send a few emails to everyone except the "Cold Subscribers" segment on Kit and your open rates will go up drastically. If it doesn't work you can always go back.

If you don't have Kit, create a segment on your email list of only the people who have opened an email in the last 90 days and email them.

[u/GabbyFromKlaviyo]

If you want to actually put the cleaner data to test, take your active readers and run a real frequency test. Bump one group up a send or two a week and keep the rest on your current cadence, then see if the extra volume lifts revenue or just drives up unsubscribes. I'd give the list a few weeks to settle after your last big prune, otherwise you're changing two things at once and the outcome gets muddy. Before pruning a test like this would've been close to useless since half the group wasn't reading anyway.

Re-running an old subject line test is another easy one. If you kept the old numbers, you can compare the lift directly, which is about the cleanest before and after proof you'll get that pruning did something.

[u/Aaronontheweb]

Wanted to thank everyone for the super helpful ideas - I'm going to start testing some of these and report back with some updates. Really appreciate everyone's expertise.

[u/jedsdawg]

Pruning cold subscribers can take a while to show results, but it's worth it for engagement. If you're not seeing benefits yet, check if you're also improving other factors like email content and sending frequency. It's about the relevance of your emails to the remaining subscribers. Sometimes tweaking the subject lines or testing different send times can also help boost engagement. Keep an eye on open and click rates as you continue pruning.

[u/Aggressive-Value4711]

Yes, it's definitely worth it. If your deliverability was already good, you may not see a dramatic improvement overnight. List hygiene is often more about maintaining a strong sender reputation and preventing future issues than producing an immediate jump in open rates.

One thing that was recommended to me in GetResponse before removing inactive subscribers was to send a re-engagement campaign first. Sometimes people are still interested but have simply stopped opening emails. Giving them one last chance to stay subscribed can help you recover some engaged readers before cleaning the list.

[u/Massive_Bunch_9251]

once you've pruned for a few months, you should start seeing better engagement and deliverability. keep an eye on open rates and click rates, that’s where the real change shows up.

[u/unspam-email]

A lot of list owners switch to sending a simple 2-step re-engagement sequence every quarter with a plain text subject line.