> For the complete documentation index, see [llms.txt](https://help.littledata.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.littledata.io/integrations/shopify-klaviyo/reducing-bounce-rate-littledata-flows.md).

# Reducing the bounce rate from Littledata flows

Why the first flow to email an address typed at checkout takes the bounce, why neither Shopify nor Klaviyo verifies those addresses, and how to verify API-created profiles before the first send.

If you compare a flow triggered by `Checkout Started - Littledata` or `Added to Cart - Littledata` with the native Klaviyo flow, the Littledata flow will usually show a higher **bounce rate**. This article explains where those bounces come from, why Shopify and Klaviyo do not catch them, and what you can do about it.

{% hint style="info" %}
Klaviyo's guideline is a bounce rate under 2%. MonitorAI checks daily for Littledata-triggered flows that go over that line.
{% endhint %}

## Where the bounces come from

An address typed at checkout is unverified. A shopper might mistype their own address, or give a deliberately false yet plausible address, or a bot fills the checkout with a generated address. When Klaviyo first emails that address and the receiving server rejects it, Klaviyo records a **hard bounce** and suppresses the profile. No later flow or campaign will email it again.

That means **only the first message ever sent** to an address can take the bounce. Whichever flow reaches a new address first carries the bounce for it, and every flow after that looks clean.

Across 40 Littledata accounts we measured how this plays out:

| Measure                                                     | Figure |
| ----------------------------------------------------------- | ------ |
| New addresses that bounced on the first email sent to them  | 1.8%   |
| Bounced emails as a share of all flow recipients            | 0.5%   |
| Share of a Littledata flow's bounces that were a first send | 86%    |
| Share of other bounces that were a first send               | 3%     |

A first send is roughly three times as likely to bounce as an average send, and a Littledata-triggered flow is almost entirely first sends.

## Why adding Littledata triggers makes this more visible

Littledata's server-side events track checkouts that Klaviyo's own onsite tracking does not: checkouts identified through Littledata's [identity graph](/integrations/shopify-klaviyo/how-it-works-shopify-to-klaviyo.md#how-events-are-matched-to-profiles) rather than a Klaviyo cookie. Those are the addresses no other flow in your account was going to email.

So a Littledata-triggered flow is the **first sender** for a larger pool of new addresses, and it inherits their first-send bounces. Littledata does not create the bounces. The addresses were entered at the checkout and would have bounced on whichever message reached them first. But the extra reach comes with the higher bounce rate attached, and the native flow next to it - which emails addresses Klaviyo already knew - does not show it.

## Why Shopify and Klaviyo do not verify these addresses

Shopify checks that the address is well formed and that the domain exists. It does **not** check whether the mailbox exists. Shopify sends the order confirmation from its own infrastructure, so when that email bounces the bounce lands on Shopify's sender, and Klaviyo is unaware.

Klaviyo validates addresses in real time only on **Klaviyo's own signup forms**. Profiles created any other way are not verified. That includes profiles created by Klaviyo's own Shopify integration when a shopper fills in the checkout email field, profiles synced from Shopify orders, and profiles created by Littledata's events. Klaviyo's protection is reactive: it suppresses an address **after** it bounces.

## Verify new profiles before the first send

Third-party verifiers can ask the receiving mail server whether a mailbox exists, without sending a message. Most of the tools that connect to Klaviyo only clean a **list** you point them at, but Littledata-triggered profiles are created by an event, so the verifier has to act on the profile **as it is created**.

[mailfloss](https://mailfloss.com/integrations/klaviyo/) does this with a native Klaviyo connection. Its **Instafloss** feature verifies every new profile as it enters Klaviyo, whichever integration created it, and suppresses the ones that fail before any flow can email them. It is free for 500 verifications a month, then $59 a month for 25,000.

{% hint style="info" %}
Verification catches mistyped and dead mailboxes. Checkouts filled in by bots are better stopped earlier: turn on [Littledata's bot filtering](/sources/shopify/bot-protection.md) for your Klaviyo connection and those events never reach Klaviyo, so the profiles are never created.
{% endhint %}

### What to check before you add a verifier

Open the `Bounced Email` metric in Klaviyo, filter to the Littledata flow, and look at `Bounce Type` and `Bounce Category`:

* Mostly **Hard** and `Invalid Address`: verification will remove most of these.
* Mostly **Soft**, or categories such as `Content` or `Reputation`: verification will not help. Review the flow content and your overall sending reputation first.
* A large share of bounces at one unusual provider, or addresses that follow a template such as `word.word1234@…`: the fix is to [enable bot filtering in Littledata](/sources/shopify/bot-protection.md#how-to-enable-bot-protection), and to follow Klaviyo's guide to [removing fake profiles](https://help.klaviyo.com/hc/en-us/articles/9890182538011) for the ones already in the account.

### Set up mailfloss

1. In mailfloss, go to **Integrations**, choose **Klaviyo** and sign in to your Klaviyo account to connect it.
2. In the Klaviyo connection settings, turn on **Instafloss**. Set the action for failed profiles to **Suppress**.
3. Leave **Fix typos** on. It corrects safe patterns such as `gmial.com` on the profile before anything is sent.
4. In your Littledata-triggered flow, keep a **Time delay** of at least an hour before the first email. Klaviyo checks suppression at send time, so a profile mailfloss suppresses during the delay is skipped.

After a week, open the `Bounced Email` metric in Klaviyo and filter to the Littledata flow. The bounces that remain should be soft bounces or older profiles, and the flow's bounce rate should be back under Klaviyo's 2% guideline.

## Learn more

* [Set up your Klaviyo flows using Littledata's triggers](/integrations/shopify-klaviyo/set-up-klaviyo-flows.md)
* [How it works: Shopify to Klaviyo](/integrations/shopify-klaviyo/how-it-works-shopify-to-klaviyo.md)
* [Klaviyo filtering: the secret to maximizing the Shopify ROI](/partner-recipes/klaviyo/klaviyo-filtering-secret-to-shopify-roi.md)