Email Deliverability for Ecommerce: What's Actually Hurting Your Inbox Placement

Deliverability is one of those terms brands throw around without really understanding what it measures. It’s not your open rate. It’s not whether Gmail likes you today. Deliverability is the percentage of your sent emails that reach the inbox, not the spam folder, not the promotions tab, not the void. Globally, 1 in 6 emails never reaches the inbox. The average inbox placement rate sits at 84% across all providers. On a healthy ecommerce list, that number should be above 95%. Most struggling brands don’t know theirs.

The good news: deliverability problems are almost always fixable. The bad news: fixing them requires understanding what’s actually causing them, and that’s where most advice falls short.

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What Deliverability Actually Measures

Inbox placement and deliverability are not the same thing as delivery rate. Klaviyo will show you a delivery rate of 99.2% and your emails can still be landing in spam for 40% of your list. “Delivered” means the receiving server accepted the email. It says nothing about where it went next.

What you actually need to track:

• Inbox placement rate: requires a tool like GlockApps, Litmus, or 250ok to measure properly
• Spam complaint rate: available in Klaviyo’s deliverability hub; keep this below 0.08% (Gmail’s threshold for reputation damage is 0.10%)
• Bounce rate: hard bounces above 0.5% on a campaign are a warning sign; above 2% is a problem. Senders who keep bounce rates under 1.5% see 10–12% higher inbox placement rates
• Unsubscribe rate: above 0.5% consistently signals mismatch between what subscribers expected and what they’re receiving

If you’re not measuring inbox placement separately from delivery rate, you’re flying blind.

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The 4 Factors That Determine Inbox Placement

1. Sender Reputation

Your sender reputation is scored at two levels: the IP address your emails are sent from, and the domain in your “From” address. Klaviyo manages shared IP pools for most accounts (unless you’re on a dedicated IP, which kicks in around 150,000+ monthly sends). This means your reputation is partly influenced by other senders on the same pool, which is another reason Klaviyo’s reputation management matters. At the extreme end, organisations sending over 1 million emails monthly with poor sender reputation face inbox placement rates below 28%.

At the domain level, your reputation is entirely your responsibility. Gmail, Yahoo, and Microsoft’s spam filters track engagement signals from every email you send from your domain. Consistent low open rates, high complaint rates, and high bounce rates erode your domain reputation over time. Domain reputation damage is much harder to recover from than IP reputation damage.

2. Engagement Rate

Mailbox providers, Gmail especially, use engagement as a primary inbox-vs-spam signal. If your subscribers routinely don’t open your emails, Gmail interprets that as a signal that the emails aren’t wanted. The threshold that matters isn’t your overall list open rate; it’s the open rate among Gmail recipients specifically, and it’s evaluated at the segment level, not just globally. Provider inbox placement rates vary significantly: Gmail averages 87.2%, Yahoo/AOL 86%, Apple Mail 76.3%, and Outlook/Hotmail only 75.6%. The same send can land in inboxes on Gmail while going to spam on Outlook.

Specific thresholds to watch in Klaviyo:

• Active segment (opened in last 90 days): should represent at least 40–50% of your total list
• If less than 30% of your list has engaged in the past 90 days, your deliverability is already under pressure
• Gmail specifically starts filtering aggressively when complaint rates exceed 0.10%. Find this in Klaviyo’s deliverability hub under Google Postmaster data if you’ve connected it

3. List Hygiene

A list full of invalid addresses, role-based emails (info@, sales@, admin@), and disengaged contacts is a deliverability liability. Every hard bounce tells the receiving server that you’re not maintaining your list. Every unengaged contact who doesn’t open is a negative engagement signal.

The common mistake: brands focus on unsubscribes and ignore the suppression-worthy contacts who simply never open. An unsubscriber is better for your deliverability than a zombie address that sits on your list receiving every campaign.

4. Authentication (SPF, DKIM, DMARC)

Authentication is the foundation. Without it, nothing else matters much because mailbox providers have no way to verify the email is actually from you. Fully DMARC-authenticated domains are 2.7× more likely to reach the inbox, yet only 18.2% of the top 10 million domains have valid DMARC records.

Klaviyo-specific setup:

• SPF: Add Klaviyo’s SPF record to your DNS. Klaviyo provides the exact records in Settings > Domains
• DKIM: Klaviyo requires DKIM verification before you can send from a custom domain. This is now mandatory and Klaviyo won’t let you send without it
• DMARC: Set a minimum policy of p=none with reporting (rua=mailto:your@email.com) to start, then move to p=quarantine once you’ve confirmed legitimate mail is passing. p=reject is the gold standard but requires careful implementation

If you set up your Klaviyo sending domain more than 12 months ago and haven’t revisited DNS settings, check again. Google and Yahoo’s 2024 requirements tightened significantly.

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How Klaviyo’s Sender Reputation Works

Klaviyo’s shared IP pools mean you benefit from their infrastructure, but you’re still responsible for domain reputation. When you send from @yourbrand.com via Klaviyo, the domain reputation associated with yourbrand.com accumulates based on your sends, regardless of what sending infrastructure handles delivery.

Klaviyo’s deliverability hub (found under Analytics > Deliverability) shows you:

• Bounce rates by campaign
• Spam complaint rates (when you’ve connected Google Postmaster Tools)
• Unsubscribe rates
• Domain health status

Connect Google Postmaster Tools, it’s free and gives you direct visibility into how Gmail specifically rates your domain. If you haven’t done this, do it today. In Klaviyo: Settings > Integrations > Google Postmaster Tools.

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Warning Signs You’re Heading Toward a Deliverability Problem

These signals appear weeks or months before you notice a major drop in revenue from email, which is why most brands miss them until it’s serious:

• Open rate declining 15–20% over 60 days without a change in send volume or list composition
• Hard bounce rate above 0.5% on a campaign (this one moves fast; a single bad import can push you above 2%)
• Complaint rate above 0.05% in Google Postmaster Tools (0.08% is where reputation damage accelerates)
• Unsubscribe rate climbing on campaigns that previously performed well
• Click-to-open rate dropping even when opens remain stable. This suggests Gmail is opening emails automatically (machine opens) while real humans are not

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What to Do When You’re Landing in Spam

If you’ve confirmed via GlockApps or a seed list test that emails are going to spam, the recovery playbook is specific:

1. Stop all broad sends immediately. Continuing to send to disengaged contacts while you’re spam-filtered makes the hole deeper.
2. Segment to your most engaged 10–15% of contacts (opened in the last 30 days, ideally with a click).
3. Send exclusively to this engaged segment for 4–6 weeks. Subject lines should be low-key and personal-feeling. Plain-text or near-plain-text emails perform better in recovery phases.
4. Check authentication. Verify SPF, DKIM, and DMARC are correctly configured and passing. Run your domain through mail-tester.com for a quick health check.
5. Suppress everyone who hasn’t opened in 180+ days. Do not delete. Suppress in Klaviyo (Audience > Suppression List). This removes them from sends without destroying the contact record.
6. Monitor Google Postmaster Tools daily during recovery. Reputation typically recovers in 4–8 weeks with disciplined sending.

The instinct when revenue drops is to send more. In a deliverability crisis, sending more is exactly wrong. Narrow first, recover reputation, then gradually re-expand your active sending list.

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The Klaviyo Settings That Matter Most for Deliverability

Most deliverability guidance talks in abstractions. Here are the specific places in Klaviyo to check:

• Settings > Domains: verify your sending domain is authenticated, DKIM is enabled, return path is configured
• Analytics > Deliverability: review bounce rates and complaint rates after every major campaign send
• Audience > Suppression List: ensure you’re regularly adding suppressions; Klaviyo automatically suppresses hard bounces, but unengaged contacts need to be added manually via segments
• Flows > [any flow] > Flow Filters: check that your automated flows exclude suppressed profiles; in most cases Klaviyo handles this, but double-check on older flows
• Campaigns > [campaign] > Smart Sending: Klaviyo’s Smart Sending feature skips contacts who received an email in the past 16 hours by default; you can adjust this, but reducing it below 8 hours increases complaint risk

Deliverability isn’t a one-time fix. It’s an ongoing operational discipline. The brands that maintain 95%+ inbox placement rates aren’t doing anything extraordinary. They’re consistently managing list hygiene, monitoring the right metrics, and sending to people who actually want their emails.

Want us to audit your deliverability setup? Book a free audit.

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Sources

• MailReach, 2025 Email Deliverability Statistics
• Validity, 2025 Email Deliverability Benchmark Report