Deliverability Starts With Who You Send To: A Klaviyo Agency's Playbook

Most ecommerce brands treat deliverability as a technical problem. They just sort out the DNS records, warm up the domain, and pat themselves on the back for a job well done.

The technical setup matters, and it's the foundation. But from where I sit, running In-box, a Klaviyo email marketing agency that has worked with more than 500 ecommerce brands, most deliverability damage is done after setup. It comes from the day-to-day marketing decisions: who gets each campaign, how often, and what the emails look like.

Here's the playbook we use to protect inbox placement while still sending enough to grow revenue.

Your deliverability score reflects your segments, not your whole account

Klaviyo's deliverability tab gives you an overall score based on metrics like the open rate, click rate, bounce rate, unsubscribe rate, and spam complaint rate. However, the score only tells you how your existing campaigns have performed. If you only email your most engaged subscribers, your score might look great even though sending to your wider list could produce very different results.

That means a healthy account can look unhealthy. Your welcome series, abandoned cart, and browse abandonment flows might be landing beautifully because they go to people who took an action on your site. Then, one campaign to your entire database gets a 20% open rate and drags the whole average down.

For example, if your flows open at around 60% but the account average sits at 40%, the flows aren't the problem. The campaign segmentation is.

Two more rules we follow when reading the tab:

Benchmark against yourself, not the industry. The "recommended" ranges compare you with every other account in your category. Aim to improve month on month.
Read every flow in context. A sunset flow should have low engagement, because it goes to unengaged people. Meanwhile, a delivered-order email should be well above the benchmark, because it's an order update people want. A plain-text post-purchase thank-you with no links will have a low click rate, and that's fine.

Klaviyo campaign report showing a 59.09% open rate for Dermavenue, managed by In-box

Source: In-box client account (Dermavenue)

Watch your bounce rate above 1%

If your bounce rate goes above 1%, find out why straight away. Bounces usually signal invalid addresses used by people who typed a fake email to get a discount, or mailboxes that are full or unavailable.

Thankfully, Klaviyo lets you break bounces down by inbox provider and by campaign or flow.

Check whether there's a one-off cause first. In one account, we saw a spike from a single provider during a known outage, which needed no action.
If there's no obvious outside cause, exclude recent bounces. Remove anyone who has bounced in the last 30 days from your campaign segments and add the same filter to your flows. In one account, that filter alone reduced the list from about 29,000 to 28,000 profiles.

Tighten the engagement window, then widen it

The lower your deliverability, the tighter the engagement window you should send campaigns to.

Our default engaged segment includes anyone who has been active on site or subscribed in the last 30 days, and/or opened or clicked an email in the last 90 days, and has bounced zero times in the last 30 days. When an account's deliverability is poor, we shrink the window to 30 days. Once open and click rates recover, we widen it again.

In one account, moving from a 30-day to a 60-day window increased the audience from 24,000 to 29,000 profiles. Depending on the account, the window we use is between 60 and 180 days.

Frequency follows the same logic. An engaged audience can usually take around 15 emails a month without major deliverability issues. Your full list, including unengaged subscribers, should get closer to three.

💡 Tip: Plan a separate content calendar for each segment rather than one calendar for the whole account.

Give Gmail reasons to move you out of Promotions

Gmail sorts emails by the signals they carry. Image-heavy layouts and sales language look like marketing, so those emails go to Promotions. Your sending history counts too, as inboxes are personalised based on how that reader has engaged with your emails before.

You may not be able to get every email into the primary inbox, but you can shift the odds:

Send a plain-text campaign about once a month. It looks like a personal email, gets more replies and positive engagement, and those signals help your future sends.
Make the first welcome email plain text. It's the email most likely to be opened, so it's the best place to build good signals early. Don't make the whole flow plain text, or Gmail learns that your plain-text emails are promotional too.
Apply for transactional status where it genuinely fits. In Klaviyo, flows triggered by a metric, such as cancelled order, refunded order, or delivered order, can be sent on transactional infrastructure, which tends to land in Updates and lifts your domain's standing.

In our experience, brands that follow these steps usually see open and click rates improve within about a month.

Stop landing in spam.Book a deliverability audit and get a clear recovery plan.Book an audit

Get the sending domain right first

None of this works without a branded sending domain. In Klaviyo, go to Settings, then Domains. Add your domain for marketing emails, and use a real address people can reply to. Add the DNS records Klaviyo gives you at your domain host, then verify. Verification can be instant or take up to 48 hours.

Get someone who knows Klaviyo to check the domain setup properly. Once that's sorted, pay attention to who you're emailing and how often.

What it looks like in real accounts

Good segmentation means you can send more emails without hurting your inbox placement. Here's how that's worked for some of our clients:

Brand	What we did	Result
Michael Gabriels (lab-grown diamond jewellery)	Buyer and non-buyer segments with engagement scoring layered on top	57% average open rate, ~30% email attribution while the business scaled 8x
Dermavenue (skincare)	Sunset and suppression logic built in from day one of the flow build	59.09% open rate across 560,040 recipients
Skinny Fizz	Cleaned up lists, segments and deliverability alongside new core flows	Email revenue up 921% within 30 days

Klaviyo deliverability report for Michael Gabriels, managed by In-box

Source: In-box client account (Michael Gabriels)

Where to start

First, open your deliverability tab and compare your flow engagement with your campaign engagement. If the flows are strong and the campaigns are weak, tighten your campaign segment before changing anything else. Then, exclude recent bounces, plan a cadence for each segment, and draft one plain-text email a month.

Loading…