Email deliverability is the silent killer of Shopify email marketing. You can write the perfect subject line, design the most beautiful template, and craft an offer your customers cannot refuse — but if your emails are landing in spam folders or promotions tabs, none of it matters. You are essentially sending love letters to a void.
What’s in This Article
Most Shopify store owners have no idea what their deliverability looks like. They check open rates and assume everything is fine. But open rates only measure the emails that actually reached the inbox. If 20% of your emails are hitting spam, your reported 25% open rate is actually masking a much bigger problem — your true reach is significantly lower than you think.
The email deliverability landscape changed dramatically in 2024 when Google and Yahoo implemented strict new requirements for bulk senders. If you are sending marketing emails to Gmail or Yahoo addresses (which together represent over 60% of Australian email users), you need to meet specific authentication and engagement requirements or risk having your emails blocked entirely.
The Three Pillars of Email Deliverability
Email deliverability comes down to three factors: authentication (proving you are who you say you are), reputation (proving you are a trustworthy sender), and engagement (proving people actually want your emails). Neglect any one of these and your deliverability will suffer.
Pillar 1: Authentication. Email authentication protocols prove to inbox providers that your emails are legitimately from your domain and have not been spoofed or tampered with. Three protocols matter: SPF (Sender Policy Framework) tells receiving servers which mail servers are authorised to send email on behalf of your domain. DKIM (DomainKeys Identified Mail) adds a digital signature to your emails that verifies they have not been altered in transit. DMARC (Domain-based Message Authentication, Reporting and Conformance) tells receiving servers what to do with emails that fail SPF or DKIM checks.
If you are using Klaviyo or Omnisend with a custom sending domain (which you should be), these platforms guide you through setting up all three protocols. It involves adding DNS records to your domain — a one-time setup that takes 15-30 minutes. If you have not done this, stop reading and go do it now. Without proper authentication, your emails are far more likely to hit spam.
Building and Protecting Sender Reputation
Pillar 2: Sender reputation. Every email you send either builds or damages your sender reputation — a score that inbox providers use to decide whether your emails deserve the inbox or the spam folder. Think of it like a credit score for email.
Clean your list regularly. Dead email addresses, spam traps, and disengaged subscribers all damage your sender reputation. Run a list cleaning at least every 90 days: remove hard bounces immediately, suppress soft bounces after 3 consecutive failures, and segment out subscribers who have not opened or clicked in 180 days. Tools like ZeroBounce or NeverBounce can identify invalid addresses before you send to them.
Warm up new sending domains. If you are switching to a new sending domain or setting up a custom domain for the first time, do not blast your entire list on day one. Start by sending only to your most engaged subscribers (opened in the last 30 days) for the first 2 weeks. Gradually increase volume over 4-6 weeks. This “warm-up” process teaches inbox providers that your domain sends emails people want to receive.
Monitor your bounce and complaint rates. Your hard bounce rate should stay below 0.5% per send. Your spam complaint rate should stay below 0.1% (Google’s new threshold). Above these numbers, you are actively damaging your reputation. If you see spikes in either metric, immediately investigate: Are you sending to stale addresses? Did you import an unverified list? Is your content triggering spam filters?
Engagement: The Metric That Rules Everything
Pillar 3: Subscriber engagement. Gmail, Yahoo, and other providers heavily weight engagement signals when deciding inbox placement. If people consistently open, click, and reply to your emails, your deliverability improves. If they consistently ignore, delete without opening, or mark as spam, it deteriorates.
Send to engaged segments first. This is the single most impactful deliverability tactic. When sending campaigns, always send first (or exclusively) to your engaged segment — subscribers who have opened or clicked in the last 90 days. These subscribers are most likely to interact with your email, which sends positive signals to inbox providers and improves placement for subsequent sends.
Sunset unengaged subscribers. If a subscriber has not opened a single email in 180 days, they are either not seeing your emails (deliverability issue) or not interested (engagement issue). Run a re-engagement campaign with a compelling subject line and clear value proposition. Those who still do not engage after 2-3 attempts should be suppressed from future sends. Yes, your list size will shrink — but your deliverability, open rates, and revenue will improve.
Optimise send frequency. Over-sending is one of the fastest ways to kill engagement and deliverability. For most Shopify stores, 2-3 campaigns per week is the sweet spot. Beyond that, you start to see diminishing returns and rising unsubscribe rates. Monitor your unsubscribe rate per campaign — if it exceeds 0.3%, you are either sending too often or your content is not relevant enough.
Technical Fixes That Improve Inbox Placement
- Use a custom sending domain. Sending from “your-store.klaviyomail.com” shares reputation with every other Klaviyo user. A custom sending domain (email.yourbrand.com.au) gives you your own reputation that you control. Set this up in your email platform settings — it requires adding CNAME records to your DNS.
- Avoid spam trigger words. Words like “free,” “guaranteed,” “act now,” “limited time,” and excessive exclamation marks can trigger spam filters. Write naturally and focus on value instead of hype. Your subject lines should sound like a person wrote them, not a used car salesman.
- Maintain a healthy text-to-image ratio. Emails that are 100% images with no text are a major spam trigger. Aim for at least 60% text, 40% images. Always include a text version of your email (most platforms do this automatically).
- Include a clear unsubscribe link. This is legally required in Australia under the Spam Act 2003, but it also helps deliverability. Making it easy to unsubscribe is better than having frustrated subscribers mark you as spam. An unsubscribe is neutral for your reputation; a spam complaint is devastating.
Monitoring Deliverability: The Dashboard You Need
Check these metrics weekly to catch deliverability issues before they become crises. Open rate trending down over 4+ weeks is the earliest warning sign. Hard bounce rate per campaign should stay under 0.5%. Spam complaint rate should remain under 0.1%. List growth rate minus unsubscribes tells you if your list is healthy. And delivery rate (emails accepted by receiving servers) should be above 98%.
Deliverability Is the Foundation of Email Revenue
You can have the best email strategy in the world, but if your emails do not reach the inbox, it is all wasted effort. Authentication, reputation, and engagement work together to determine whether your emails get seen or get buried. Fix these fundamentals first, then focus on optimising content and timing. A 10% improvement in deliverability can translate to a 10% increase in email revenue — with zero extra effort on the content side.
Inside the eCommerce Circle, email deliverability is one of the first things we audit under our Promotion pillar. If your open rates are declining and you are not sure why, or if you have never set up proper email authentication, our coaching walks you through the technical setup and ongoing monitoring that keeps your emails in the inbox where they belong.
