Email deliverability is the ability of your emails to reach subscribers’ inboxes rather than their spam folders or promotions tabs. For ecommerce brands, poor email deliverability means your highest-revenue automations, including welcome series, abandoned cart flows, and post-purchase sequences, are firing on schedule but never being seen. A flow that converts at 5% with good inbox placement converts at near zero when it lands in spam. Deliverability is not a technical edge case. It is the foundation everything else in your email program sits on.
This post covers the five factors that determine email deliverability, the most common causes of deliverability problems for ecommerce stores, and the steps to diagnose and fix them.
Are your email flows actually reaching the inbox?
AI Advantage Agency audits and optimizes email and SMS programs for Shopify and WooCommerce brands. If your flows are underperforming, deliverability is often the first place to look.
The Quick Take: Poor Email Deliverability vs Strong Email Deliverability
| Poor Email Deliverability | Strong Email Deliverability |
|---|---|
| Inbox placement: Spam or promotions tab | Inbox placement: Primary inbox consistently |
| Open rates: Below 15% with no clear cause | Open rates: 30 to 50% on engaged segments |
| Sender reputation: Flagged or degraded domain | Sender reputation: Trusted domain with clean history |
| Flow performance: Revenue below benchmark despite correct setup | Flow performance: Automations generating expected revenue per recipient |
| List health: High bounce and complaint rates | List health: Low bounces, suppression lists maintained |
💡 Pro Tip: Email deliverability problems are almost always gradual, not sudden. Open rates drop slowly over weeks before the pattern becomes obvious. Check your open rate trend monthly, not just your last send. A 5-point drop over two months is a deliverability signal, not normal variance.
The Takeaway: Email deliverability is the precondition for everything else in your email program. A technically perfect flow with poor inbox placement generates almost no revenue.
Table of Contents
→ The Five Factors That Determine Email Deliverability
→ The Most Common Causes of Deliverability Problems for Ecommerce
→ How to Warm Up a New Sending Domain
→ List Hygiene: The Deliverability Factor Most Brands Ignore
→ How to Diagnose an Email Deliverability Problem
→ Technical Setup: SPF, DKIM, and DMARC for Ecommerce Senders
→ The Bottom Line on Email Deliverability
→ FAQ: Common Questions
The Five Factors That Determine Email Deliverability
Email deliverability is determined by five interconnected factors: sender reputation, authentication, list quality, engagement signals, and content. Internet service providers and inbox providers like Gmail and Outlook evaluate all five when deciding where to route an incoming email. Weakness in any one factor can override strength in the others.
| Factor | What It Means and Why It Matters |
|---|---|
| Sender reputation | A score assigned to your sending domain and IP based on past send history. High complaint rates and spam traps degrade it fast. |
| Authentication | SPF, DKIM, and DMARC records prove you are authorized to send from your domain. Missing records cause automatic filtering. |
| List quality | The proportion of valid, opted-in addresses on your list. Stale, purchased, or unverified addresses inflate bounce rates and trigger spam filters. |
| Engagement signals | Opens, clicks, and replies signal to inbox providers that subscribers want your emails. Sending to chronically unengaged subscribers drags your reputation down. |
| Content | Spam trigger words, heavy image-to-text ratios, and broken links are content signals that filter algorithms use to route emails to spam. |
💡 Pro Tip: Sender reputation is the hardest factor to recover once damaged. Authentication and content issues can be fixed in hours. A degraded domain reputation can take weeks of careful sending to rebuild. Protect your reputation proactively rather than repairing it reactively.
The Most Common Causes of Deliverability Problems for Ecommerce
Most ecommerce email deliverability problems trace back to three behaviors: sending to unengaged subscribers, neglecting list suppression, and launching flows on cold domains. These are not one-time mistakes. They are structural problems that compound over time and become harder to reverse the longer they run.
Poor email deliverability hits your highest-value flows hardest. Behavior-triggered automations like browse abandonment emails and back-in-stock emails depend entirely on inbox placement to generate revenue. If those flows are underperforming, deliverability is the first place to look.
Sending to unengaged subscribers. Every email sent to a subscriber who has not opened or clicked in 90 to 180 days is a signal to inbox providers that your emails are not wanted. This affects your highest-value flows first. Browse abandonment and back-in-stock emails depend on inbox placement to generate revenue. Gmail and Outlook measure engagement at the domain level. A large unengaged segment depresses your overall engagement rate and trains inbox providers to route your emails away from the primary inbox. The fix is aggressive segmentation that excludes chronically unengaged subscribers from your regular sends.
Missing suppression lists. Hard bounces, spam complaints, and unsubscribes must be suppressed immediately. Continuing to send to addresses that bounced or complained is one of the fastest ways to degrade sender reputation. Most email platforms handle unsubscribes automatically, but hard bounce suppression and complaint processing sometimes require manual configuration. Check your suppression list settings in Klaviyo or your platform of choice before your first large send.
Sending high volume from a cold domain. Launching a new sending domain and immediately sending 50,000 emails is a guaranteed deliverability failure. Inbox providers have no positive history for your domain and will route aggressively to spam. New domains require a warmup period of gradual volume increases before they can handle large sends reliably.
Purchased or scraped lists. Lists that were not organically grown through opt-in mechanisms contain invalid addresses, spam traps, and contacts who never consented to receive your emails. Sending to these lists damages sender reputation immediately and can result in domain blacklisting. No ecommerce email program should ever use a purchased list.
How to Warm Up a New Sending Domain
Domain warmup is the process of gradually increasing send volume from a new domain to build a positive sending reputation with inbox providers before scaling to full list size. Skipping warmup is the single most common cause of catastrophic email deliverability failure for brands launching new programs or switching email platforms.
The warmup process works by starting with small sends to your most engaged subscribers, generating strong open and click signals, then incrementally increasing volume over four to eight weeks. Your most engaged segment is typically recent purchasers and subscribers who opened a welcome email series within the last 30 days. Inbox providers see consistent positive engagement from your domain and progressively extend it more trust.
A standard warmup ramp for ecommerce looks like this. Week one: 200 to 500 emails per day to your highest-engagement segment. Week two: 1,000 to 2,000 per day. Week three: 5,000 per day. Week four and beyond: double weekly until you reach your full send volume. Monitor bounce rates, spam complaint rates, and open rates at each stage. If metrics degrade, slow the ramp and stay at the current volume until they stabilize.
Klaviyo and other major email platforms publish warmup guidelines specific to their infrastructure. (Klaviyo Help Center, Dedicated Sending Infrastructure, 2024.) Following the platform’s recommended ramp is safer than building your own schedule from scratch.
💡 Pro Tip: Define your highest-engagement segment as subscribers who have opened or clicked in the last 30 days. Do not include anyone with no engagement in the last 90 days in your warmup sends. Starting warmup with disengaged contacts undermines the entire purpose of the process.
List Hygiene: The Deliverability Factor Most Brands Ignore
List hygiene is the ongoing practice of removing invalid, bounced, unengaged, and spam-trap addresses from your sending list. For ecommerce brands that grow lists aggressively through popups and promotions, list hygiene is not a one-time cleanup. It is a continuous process that determines whether your email deliverability improves or degrades over time.
The core list hygiene practices for ecommerce senders are:
Suppress hard bounces immediately. A hard bounce means the address does not exist or is permanently unreachable. Sending to it again is a direct sender reputation signal. Your email platform should suppress hard bounces automatically, but verify this is configured correctly rather than assuming.
Remove or suppress chronic non-openers. Subscribers who have not opened an email in 180 days are hurting your engagement rate with every send. Run a sunset flow, a re-engagement sequence with a clear final ask, and suppress anyone who does not respond. For a structured approach to re-engagement, see the ecommerce email flows guide, which covers the sunset flow in detail.
Use double opt-in for new subscribers. Double opt-in requires a new subscriber to confirm their email address before being added to your list. It reduces list growth speed but eliminates typo addresses, fake signups, and low-intent contacts that inflate your list size while damaging email deliverability. For high-traffic ecommerce stores running aggressive popup strategies, double opt-in is often the most effective single change for long-term deliverability health.
How to Diagnose an Email Deliverability Problem
Most email deliverability problems are invisible until they are severe. By the time open rates drop noticeably, the underlying issue has usually been degrading for weeks. A structured diagnostic process catches problems earlier.
Step 1: Check your sending domain reputation. Use Google Postmaster Tools to see your domain reputation score for Gmail, which represents the largest inbox provider by volume for most ecommerce brands. A “Low” or “Bad” reputation rating explains low Gmail open rates immediately. Google Postmaster Tools is free and connects to your domain via DNS verification. (Google Postmaster Tools.)
Step 2: Check authentication records. Verify that SPF, DKIM, and DMARC records are correctly configured for your sending domain. Your email platform’s setup documentation will specify the exact DNS records required. Missing or misconfigured records cause filtering even when your reputation is clean.
Your choice of email platform also affects how much visibility you have into deliverability issues. See the Klaviyo vs Omnisend comparison for how each platform handles deliverability reporting and sender reputation monitoring. Step 3: Segment open rates by inbox provider. Klaviyo and most major platforms let you filter campaign and flow performance by email domain (gmail.com, yahoo.com, outlook.com). If open rates are low specifically on Gmail but normal elsewhere, your domain reputation with Google is the problem. If open rates are uniformly low across all providers, authentication or content is more likely the cause.
Step 4: Audit your suppression list and bounce rate. A hard bounce rate above 2% on any send is a serious deliverability signal. Check your suppression list to confirm that bounced and unsubscribed addresses are being excluded from all sends.
Technical Setup: SPF, DKIM, and DMARC for Ecommerce Senders
SPF, DKIM, and DMARC are DNS authentication records that prove to inbox providers that your emails are legitimately sent from your domain. Without all three configured correctly, inbox providers cannot verify your identity and will route your emails to spam regardless of your sender reputation or list quality.
SPF (Sender Policy Framework) lists the mail servers authorized to send email from your domain. When you send through Klaviyo, Mailchimp, or any email platform, their sending servers need to be included in your SPF record. Most platforms provide the exact SPF record string to add to your domain’s DNS.
DKIM (DomainKeys Identified Mail) adds a cryptographic signature to each email that proves the message was not altered in transit and was sent by an authorized server. Your email platform generates a DKIM key that you add to your DNS as a TXT record.
DMARC (Domain-based Message Authentication, Reporting, and Conformance) tells inbox providers what to do when an email fails SPF or DKIM checks: reject it, quarantine it, or deliver it. A DMARC policy at the “reject” level provides the strongest protection against domain spoofing and is required by Gmail and Yahoo for bulk senders as of 2024.
For most Shopify brands using Klaviyo, the platform’s onboarding flow walks through the required DNS records. If you are still evaluating which platform to use, the Klaviyo vs Omnisend comparison covers how each platform handles authentication setup and deliverability tooling. The key is verifying the records are live using a DNS checker tool before sending at scale.
💡 Pro Tip: Use a dedicated sending subdomain (mail.yourdomain.com or send.yourdomain.com) rather than your root domain for email sends. This isolates your email sending reputation from your root domain’s web reputation. If email deliverability degrades, it does not affect your website’s domain authority or search rankings.
The Bottom Line on Email Deliverability
Email deliverability is not a one-time configuration task. It is an ongoing discipline that requires consistent attention to list hygiene, engagement segmentation, and authentication health. For ecommerce brands investing in email flows and campaigns, poor email deliverability silently cancels the return on that investment by routing messages away from the subscribers they are built to reach.
The most important things to get right first are authentication records and suppression configuration. Both are technical fixes that take hours to implement and have an immediate positive impact on inbox placement. List hygiene and engagement segmentation are ongoing practices that compound over months into significantly stronger sender reputation.
If your email flows are underperforming and you cannot explain why, email deliverability is the first place to look. Check your domain reputation in Google Postmaster Tools, verify your authentication records, and pull your open rates by inbox provider. The data will tell you exactly where the problem is.
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Frequently Asked Questions About Email Deliverability
What is email deliverability?
Email deliverability is the ability of your emails to reach subscribers’ inboxes rather than their spam folders or promotions tabs. It is determined by sender reputation, authentication records, list quality, engagement signals, and email content. Poor deliverability means your automations and campaigns are sending but not being seen.
Why are my ecommerce emails going to spam?
The most common causes are missing or misconfigured authentication records (SPF, DKIM, DMARC), a degraded sender domain reputation from high complaint rates or sending to unengaged subscribers, high bounce rates from invalid addresses, or spam trigger words in email content. Check Google Postmaster Tools and your authentication records first.
What is sender reputation and how does it affect email deliverability?
Sender reputation is a score assigned to your sending domain and IP address based on your email sending history. High spam complaint rates, hard bounces, and sending to unengaged subscribers degrade it over time. Inbox providers use sender reputation as a primary signal to decide whether to deliver, filter, or block your emails.
What is domain warmup and why does it matter?
Domain warmup is the process of gradually increasing send volume from a new sending domain to build a positive reputation with inbox providers before scaling to full list size. Skipping warmup and sending high volumes immediately from a new domain causes immediate spam filtering. A standard warmup takes four to eight weeks of incremental volume increases.
How do I check my email deliverability?
Use Google Postmaster Tools to check your domain reputation with Gmail. Verify SPF, DKIM, and DMARC records are correctly configured using a DNS checker. Segment open rates by inbox provider in your email platform to identify whether deliverability problems are Gmail-specific or across all providers. Check hard bounce rates on recent sends.
What is list hygiene and how does it improve email deliverability?
List hygiene is the ongoing practice of removing invalid, bounced, unengaged, and spam-trap addresses from your sending list. It improves email deliverability by reducing hard bounce rates, lowering spam complaint rates, and increasing overall engagement rates. All of these strengthen sender reputation over time.
What are SPF, DKIM, and DMARC?
SPF, DKIM, and DMARC are DNS authentication records that prove to inbox providers that your emails are legitimately sent from your domain. SPF lists authorized sending servers. DKIM adds a cryptographic signature to each email. DMARC tells inbox providers what to do when emails fail authentication checks. All three are required for reliable inbox placement.
How often should I clean my email list?
Suppress hard bounces immediately after every send. Run a re-engagement or sunset flow for subscribers who have not opened or clicked in 180 days, and suppress non-responders. For high-volume senders, a quarterly list hygiene audit is a minimum. For brands running aggressive list-growth campaigns, monthly audits are more appropriate.
Does sending frequency affect email deliverability?
Yes. Sending too frequently to unengaged subscribers accelerates reputation degradation by generating more low-engagement signals per subscriber per week. Sending too infrequently to a large dormant list and then resuming high-volume sends looks like unusual activity to inbox providers. Consistent frequency to engaged segments is the safest pattern.
What open rate indicates an email deliverability problem?
There is no single threshold, but open rates below 15% on sends to your full list, or a consistent downward trend of 5 or more percentage points over two to three months, warrant a deliverability audit. Compare open rates by inbox provider to identify whether the problem is platform-specific. A sudden drop on Gmail specifically points to domain reputation issues with Google.
