Ecommerce Email Deliverability

Ecommerce email deliverability: how to stay out of spam

You can have the best email program in your category — sharp copy, beautiful design, perfectly timed flows — and still make almost nothing from it, if your emails are landing in spam. Deliverability is the invisible tax on ecommerce email. Most brands don't know they're paying it, because the symptom is simply revenue that quietly underperforms for reasons nobody can name.

The frustrating part is that deliverability isn't mysterious. It runs on a small set of rules, and once you understand them, the fixes are clear. This is the guide we wish every DTC brand read before they started blaming their copy for a problem that was really about inbox placement.

What deliverability actually is

Deliverability is your reputation as a sender, expressed as a probability that your email reaches the primary inbox rather than spam or the promotions pile. Inbox providers like Gmail and Outlook calculate that reputation, and the single biggest input is engagement. If the people you email open, click and reply, providers conclude your mail is wanted and deliver it. If they ignore or delete it, providers conclude the opposite and start filtering.

This is the mental model that fixes most deliverability problems: you are not sending to inboxes, you are earning your way into them, one engaged send at a time. Everything below is a way of protecting that engagement signal.

Get your authentication right

Before anything else, the technical foundation has to be in place. Three records prove to providers that you are really you and that nobody is spoofing your domain: SPF, DKIM and DMARC. If these aren't set up correctly, a share of your mail gets filtered before engagement even enters the picture, and you'll never diagnose it from the campaign dashboard.

This is a one-time setup for most brands, but it's astonishing how many skip it or configure it wrong, then spend months wondering why deliverability is poor. If you take one technical action from this article, confirm your authentication is correct. It's the floor everything else stands on.

Stop emailing people who never open

The most common cause of poor deliverability is also the most counterintuitive to fix. Every brand accumulates dead weight: subscribers who signed up once and haven't opened an email in six months or a year. It feels wasteful to stop emailing them — they're on the list, why not try? But their silence is actively hurting you. A list full of non-openers drags down your aggregate engagement rate, which drags down your reputation, which pushes even your engaged customers toward spam.

The fix is a sunset flow: a defined process that identifies chronically unengaged contacts, makes one last attempt to win them back, and then suppresses the ones who still don't respond. Emailing fewer people is how you reach more of them, because your engagement rate climbs and your best customers land in the inbox again. This is a core part of any Klaviyo flow audit, and it's usually the single highest-return change a neglected account can make.

Send by engagement, not to everyone

Related to list hygiene is sending strategy. The lazy default is to blast every campaign to the entire list. It feels productive and it slowly poisons your reputation. The disciplined alternative is engagement-based sending: your highest-frequency campaigns go to your most engaged segments, and unengaged contacts hear from you far less often, if at all.

This does two things at once. It concentrates your sending on the people most likely to open, which keeps your engagement rate high. And it protects the unengaged from being pushed further into disengagement by mail they were never going to open. Good email marketing is as much about who you don't send to as who you do.

Engagement content is deliverability content

Because engagement drives reputation, anything that makes your email more engaging also makes it more deliverable. Relevant, segmented messages get opened more than generic blasts. Emails built around genuine customer proof — the kind a strong review program produces — earn more clicks than pure brand claims. Your automated flows, which reach people at moments of high intent, almost always out-engage broadcast campaigns, which is why a healthy flow foundation quietly supports your deliverability too. The core flows every store needs are doing double duty: earning revenue and protecting your inbox placement.

The warning signs

Deliverability problems are easy to miss because they rarely announce themselves. Watch for open rates drifting down month over month with no other explanation. Campaigns that used to convert going quiet. A widening gap between the size of your list and the revenue it produces. A spike in the share of your audience that hasn't engaged in 90 days. Any of these is a signal to investigate placement before you touch anything else.

To diagnose, use seed testing (sending to a set of monitored inboxes to see where you land), watch your engagement trend by segment, and check your domain reputation in the tools providers make available. The point is to catch a slide early, because the longer poor placement persists, the harder the reputation is to rebuild.

Have a channel that doesn't depend on the inbox

Finally, deliverability is a reason not to put every egg in the email basket. When inbox placement dips, or when a message genuinely can't afford to be filtered, a well-run SMS program gives you a direct line that doesn't depend on a provider's spam algorithm at all. It isn't a replacement for email, but it's a resilient complement, and coordinating the two means an important message can always reach a high-intent customer somehow.

Two deliverability myths to drop

First, "our spam complaint rate is low, so we're fine." Complaint rate is only one signal, and a lagging one. You can have almost no complaints and still be quietly filtered to the promotions tab or spam because your engagement is weak. The absence of complaints is not the presence of good placement.

Second, "a bigger list means more revenue." The opposite is usually true. Adding unengaged or poorly-sourced contacts drags your aggregate engagement down and can pull your whole program toward spam, taking your existing, healthy subscribers with it. A smaller list you can actually reach beats a bigger one you can't. Growth has to be earned with quality opt-ins, not bought in bulk.

The compounding payoff

Here's why deliverability is worth the effort: the fix compounds. Repair authentication, clean the list, send by engagement, and inbox placement recovers — which lifts the performance of every single email you send afterward, automatically and forever, until you let the discipline slip. It's the rare project where the work you do once keeps paying out on all future sends. That's exactly why a retention partner audits deliverability first, before optimising a single campaign that might be landing in a folder nobody opens.

Frequently asked questions

Why are my emails going to spam?

Usually because your engagement rate is low, often from emailing too many unengaged contacts, or because your domain authentication (SPF, DKIM, DMARC) isn't set up correctly. Inbox providers use engagement and authentication as their main signals, so both need to be right.

Does removing subscribers really improve deliverability?

Yes. Suppressing chronically unengaged contacts raises your aggregate engagement rate, which improves your sender reputation and gets your remaining, active subscribers into the inbox more reliably. Emailing fewer people often means reaching more of the ones who matter.

Have us audit and rebuild your inbox placement through our email services, starting with a flow and deliverability audit. Request an Audit →