Klaviyo Bounced Emails: Soft vs Hard, and How to Fix Them

A bounce is the one email metric that’s almost entirely under your control. Opens depend on subject lines and inbox placement, and clicks depend on content. Bounces mostly come down to how you collect addresses and how you look after the list afterwards. Klaviyo does a lot of the clean-up automatically, but its rules are specific, and a few of them catch brands out, especially after a migration or a big import.

This guide covers how Klaviyo classifies bounces, when it suppresses a profile, what a healthy rate looks like and how to bring a rising one back down.

---

What is a bounced email in Klaviyo?

A bounced email is one the recipient’s mail server refused to accept. Klaviyo logs a hard bounce when the reason is permanent, such as a non-existent address, and suppresses that profile immediately. It logs a soft bounce when the reason is temporary, such as a full inbox, and only suppresses after more than seven consecutive soft bounces.

Those rules are from Klaviyo’s bounce documentation as of September 2026. Once a profile is suppressed, for either reason, Klaviyo also removes it from any lists it was on.

---

Soft bounce vs hard bounce

	Hard bounce	Soft bounce
Cause	Permanent: address or domain doesn’t exist, account closed	Temporary: inbox full, server down, message too large, rate limiting
Klaviyo’s action	Suppressed immediately	Suppressed after more than 7 consecutive soft bounces
Counting window	Single event	Only soft bounces from the past 2 years count
Can it recover?	Not through a subscribe action	Yes, a delivered email resets the run
What it tells you	Where addresses came from	Often, how the receiving server sees you

Klaviyo’s own recommendation is not to wait for the seven-bounce limit. Its guide to reducing bounce rates suggests a segment of anyone with at least four bounced emails in the last 90 days who can receive email marketing, then suppressing that segment proactively. We run it monthly on every account we manage.

The ten bounce categories

Klaviyo sorts bounces into categories in the deliverability hub. The category tells you where to look.

Category	What it usually means	Where to look first
Invalid address	Typos, fake sign-ups, dead addresses	Sign-up forms, old imports
Mailbox unavailable	Inbox full or disabled	Long-inactive subscribers
Invalid sender address	A problem with your From address or domain	Sending domain setup
Reputation	The receiving server distrusts your domain or IP	Authentication, complaints, engagement
Content	Something in the message triggered filtering	Links, attachments, spam-like copy
Frequency or volume too high	You’re sending faster than the server accepts	Send volume spikes, big blasts to cold lists
Message size / message length	Email too heavy	Image-heavy templates, embedded code
Technical	Server-side errors	Usually transient; watch for patterns
Unclassified	The receiving server didn’t give a usable reason	Check by mailbox provider

Invalid address and mailbox unavailable are list problems. Reputation, content and frequency are deliverability problems that happen to show up as bounces, and they need a different fix.

---

Suppressions: what they are and what they cost

A suppressed profile stays in your account but can’t receive marketing email. Per Klaviyo’s suppression guide, profiles are suppressed for:

• A hard bounce
• Soft bounces more than seven times in a row
• A spam complaint
• Manual suppression by you
• A legacy suppression carried over from a previous email platform

Unsubscribes work differently. They’re a consent status, not a suppression.

Three things follow from that:

1. Suppressed profiles don’t count toward your bill. Klaviyo doesn’t charge for them, which is one reason bounce clean-up matters more under its active-profile pricing. See our Klaviyo pricing guide.
2. Deliverability suppressions stick. Klaviyo lifts manual suppressions on request, and a resubscribe lifts non-deliverability suppressions. Hard bounces and spam complaints are not removed by a subscribe action. That’s deliberate: it stops a bad address being fed back in through a form.
3. “Suspicious” addresses are a separate category. If an address has hard bounced at least once anywhere across Klaviyo’s infrastructure, Klaviyo marks it as suspicious and skips it automatically, even if it never bounced in your account. If a customer insists the address works, Klaviyo support can review it with evidence, such as a screenshot showing delivery after the date it was marked.

---

What’s a good bounce rate in Klaviyo?

Klaviyo’s deliverability monitoring guidance uses these bands:

Bounce rate	Klaviyo’s status
Under 1%	Healthy
1% to 2%	Room for improvement
Over 2%	Needs attention

In practice, engaged segments on a well-kept list sit comfortably under the 1% line. A single campaign spiking over 2% usually means you sent to a segment you don’t normally mail, such as an old import or a “everyone in the account” list. A gradual rise across every send points to list decay or a problem at the point of capture.

---

How to find bounced emails in Klaviyo

• Deliverability hub: Analytics → Deliverability. Bounce rate over time, a heatmap and the top bounce categories.
• Bounce report: counts and percentages by category, with drill-down.
• Segments: build on the Bounced Email metric (for example, bounced at least once in the last 30 days) to see and act on individual profiles.
• Profiles: a single profile’s activity feed shows each bounce event.
• Campaigns and flows: the recipient activity tab shows bounces for a specific send.
• Suppressed profiles: Profiles → View suppressed profiles (top right), then filter by email bounce.

---

How to fix a high bounce rate in Klaviyo

Work through these in order. Each step rules out a cause before you move to the next.

1. Find out which bounces you have. Check the category breakdown first. A list problem and a reputation problem look the same in the headline rate but need opposite fixes.

2. Trace invalid addresses to the source. Filter bounced profiles by source or list. If they cluster on one sign-up form, check it for bot submissions and typo-prone fields. If they come from an import, that import needs cleaning or re-permissioning before you mail it again. Klaviyo sets lists to double opt-in by default and recommends keeping it on. If you’ve turned it off, bounces are one of the costs.

3. Suppress repeat soft bouncers early. Build Klaviyo’s recommended segment (four or more bounces in the last 90 days, still emailable) and suppress it. Don’t wait for the seven-in-a-row rule.

4. Clean up after migrations. Most bounce spikes we investigate follow a platform switch. If contacts that were “cleaned” in the old platform already existed in Klaviyo when you connected, the migration may not have suppressed them. Our Klaviyo Mailchimp integration guide covers that exact trap. Upload the old platform’s bounced and cleaned exports to your suppression list before your first big send.

5. Stop mailing people who’ve gone quiet. Addresses that haven’t opened or clicked in six to twelve months are the ones most likely to be abandoned, disabled or converted into spam traps. Engagement-based sending segments and a sunset flow keep them off your sends. The full method is in our list cleaning guide.

6. If the categories say reputation, content or frequency, fix deliverability. Check SPF, DKIM and DMARC on your branded sending domain (our email deliverability checker does this in seconds), look at bounces by mailbox provider, and slow down volume to any provider that’s pushing back. A spike limited to Microsoft addresses (Outlook, Hotmail) while Gmail looks fine is a common pattern, and it means your reputation with that one provider needs work. Our email deliverability guide goes through the full diagnostic.

Why am I getting bounce messages for emails I didn’t send?

That’s usually backscatter: someone is sending spam with your domain in the From address, and the bounces come back to you. It isn’t a Klaviyo bounce and won’t show in your Klaviyo reporting. The protection is a DMARC policy on your domain that moves to quarantine or reject once your legitimate senders are all authenticated.

---

Bounces are a symptom

A bounce rate over 1% is rarely the problem itself. It points to a capture problem, a list that’s aged without maintenance, or a reputation issue showing up as rejections. Klaviyo’s automatic suppression stops the damage getting worse. It doesn’t fix the cause. If your rate is climbing, or Klaviyo has flagged your account, our email deliverability service finds the source and fixes it. Every free Klaviyo audit we run starts with a deliverability check that includes your bounce categories.