An actionable guide to inbox placement: SPF/DKIM/DMARC setup, sender reputation monitoring, list hygiene, engagement metrics, and the warning signs that your delivery rate is about to tank.
StoreWiz Team
Feb 9, 2026 · 12 min read
Email deliverability is the difference between emails reaching the inbox and emails going to spam. In 2026, Google and Yahoo enforce strict sender requirements: DMARC, DKIM, and SPF authentication are mandatory; spam complaint rates must stay below 0.1%; and one-click unsubscribe is required. If you send 5,000+ emails per month without these in place, up to 40% of your emails may never reach the inbox. The fix is technical setup (30 minutes), list hygiene (monthly), and sending practices that keep engagement high and complaints low.
You can write the best email copy in the world, but if it lands in spam, nobody reads it. Email deliverability—the percentage of your emails that actually reach the recipient's inbox—is the silent killer of ecommerce email programs. Most stores have no idea their deliverability is bad until they notice email revenue declining.
The landscape changed dramatically in early 2024 when Google and Yahoo rolled out new sender requirements. Stores that didn't comply saw open rates drop 30–50% overnight. Those requirements are now enforced by every major inbox provider, and they're getting stricter.
This guide covers the technical setup, list management, and sending practices that keep your emails in the inbox. Whether you use Klaviyo, Omnisend, Mailchimp, or any other platform, these requirements apply.
Email authentication proves that you are who you say you are. Without it, inbox providers treat your emails as potentially fraudulent and route them to spam. There are three protocols you need:
| Protocol | What It Does | Setup Difficulty | Mandatory? |
|---|---|---|---|
| SPF (Sender Policy Framework) | Specifies which mail servers are authorized to send email on behalf of your domain | Easy (DNS TXT record) | Yes (Google/Yahoo requirement) |
| DKIM (DomainKeys Identified Mail) | Adds a digital signature to your emails proving they haven't been tampered with | Easy (DNS CNAME records) | Yes (Google/Yahoo requirement) |
| DMARC (Domain-based Message Authentication) | Tells inbox providers what to do with emails that fail SPF/DKIM checks (reject, quarantine, or allow) | Easy (DNS TXT record) | Yes (Google/Yahoo requirement) |
Step 1: Check current status
Use a free tool like MXToolbox, Google's Check MX, or mail-tester.com to see which protocols you're missing. Send a test email to check@mail-tester.com for a detailed report.
Step 2: Set up SPF
Add a TXT record to your domain's DNS with your email platform's SPF include. Example: v=spf1 include:_spf.google.com include:sendgrid.net ~all. Your email platform (Klaviyo, Omnisend, etc.) provides the exact record.
Step 3: Set up DKIM
Your email platform generates DKIM keys. Add the CNAME records they provide to your DNS. This is usually 2-3 records. Klaviyo, Omnisend, and Mailchimp all have one-click setup guides.
Step 4: Set up DMARC
Add a TXT record: v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com. Start with p=none (monitoring only). After 2-4 weeks of clean data, upgrade to p=quarantine, then p=reject.
Step 5: Verify with a test
Send another test email to mail-tester.com. You should score 9/10 or 10/10. If SPF, DKIM, or DMARC are still failing, check your DNS propagation (can take up to 48 hours).
If you send more than 5,000 emails per day to Gmail or Yahoo users (which most ecommerce stores do), you must comply with these requirements or risk deliverability penalties:
SPF + DKIM + DMARC authentication
All three protocols must be properly configured. Missing any one of them can trigger spam filtering.
Spam complaint rate below 0.1%
If more than 1 in 1,000 recipients mark your email as spam, your sender reputation degrades. Monitor this in Google Postmaster Tools (free).
One-click unsubscribe header
Every marketing email must include a List-Unsubscribe header that lets users unsubscribe in one click without visiting a landing page. Most email platforms add this automatically.
Valid forward and reverse DNS
Your sending IP addresses must have proper PTR records. This is handled by your email platform if you use shared IPs, or by you if you use a dedicated IP.
TLS encryption for transit
Emails must be sent over TLS (encrypted connection). All major email platforms support this by default.
Send from your own domain
Stop sending from gmail.com, yahoo.com, or your email platform's default domain. Use your branded domain (e.g., hello@yourstore.com).
A dirty list (full of invalid emails, spam traps, and disengaged subscribers) is the #1 cause of deliverability problems. Here's the monthly cleaning process:
Remove hard bounces immediately. Any email that bounces (invalid address) should be automatically suppressed. Your email platform should handle this, but verify it's working.
Suppress 120-day non-openers from regular campaigns. If someone hasn't opened an email in 4 months, move them to a re-engagement segment—don't keep mailing them.
Run a re-engagement sequence for 90-day non-openers. Send 2-3 emails: "We miss you" + incentive + "Last chance before we remove you." Anyone who doesn't engage after the sequence gets suppressed.
Validate new subscribers with double opt-in or email verification services (NeverBounce, ZeroBounce). This prevents fake emails and typos from polluting your list.
Monitor your spam complaint rate in Google Postmaster Tools weekly. If it exceeds 0.05%, investigate which campaigns are triggering complaints and adjust.
Remove role-based emails (info@, admin@, support@) and known spam trap domains. These are signals of a poorly maintained list.
Automated Monitoring
StoreWiz monitors deliverability health 24/7 and auto-cleans your list by removing hard bounces, spam complaints, and inactive subscribers before they hurt your sender reputation. This proactive hygiene keeps your rates above 98% without manual intervention.
| Practice | Why It Helps | What to Avoid |
|---|---|---|
| Consistent send volume | Sudden spikes trigger spam filters | Sending 50K emails after weeks of sending 5K |
| Segment by engagement | Engaged subscribers signal inbox placement | Sending to entire list including inactive contacts |
| Relevant content per segment | Higher opens and clicks = better reputation | Same generic email to every subscriber |
| Clear sender name and subject | Recipients recognize you, don't mark as spam | Misleading subjects, changing sender name frequently |
| Text-to-image balance | Image-heavy emails trigger spam filters | All-image emails with no text content |
| Working unsubscribe link | Mandatory, prevents spam complaints | Broken or hard-to-find unsubscribe links |
You can't fix what you can't measure. Set up these free monitoring tools:
Google Postmaster Tools
Shows your domain reputation, spam rate, authentication results, and delivery errors for Gmail recipients. Free. Set up at postmaster.google.com.
Mail-tester.com
Send a test email, get a 0-10 score with specific feedback on authentication, content, and blacklists. Free for 3 tests/day.
Your email platform's analytics
Monitor open rates (below 15% = problem), bounce rates (above 2% = problem), and spam complaint rates (above 0.05% = warning, above 0.1% = urgent).
MXToolbox blacklist check
Checks if your sending domain or IP is on any email blacklists. Run monthly at mxtoolbox.com/blacklists.aspx.
Three signals: (1) Open rates suddenly drop below 15% (typical ecommerce open rates are 20–35%). (2) Google Postmaster Tools shows a “Bad” domain reputation. (3) You're getting fewer replies and forwards than usual. You can also create test accounts on Gmail, Yahoo, and Outlook and check where your emails land.
For most ecommerce stores (sending under 100K emails/month), a shared IP from your email platform is fine and easier to manage. Dedicated IPs only make sense if you send 100K+ emails monthly and have the expertise to warm and maintain the IP. A poorly managed dedicated IP is worse than a good shared IP.
Typically 2–8 weeks. The recovery process: (1) Stop sending to disengaged subscribers immediately. (2) Send only to your most engaged segment (30-day openers) for 2 weeks. (3) Gradually expand your sending to 60-day, then 90-day openers. (4) Monitor Google Postmaster Tools until your reputation improves to “Medium” or “High.” During recovery, reduce send volume and frequency.
Written by StoreWiz Team
Deliverability Expert
The StoreWiz team writes about ecommerce automation, AI operations, and growth strategies for modern online sellers. Our insights come from building technology that helps brands scale without scaling headcount.
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