Email Deliverability Guide for US E-Commerce Brands: Get Out of the Spam Folder

An email that lands in spam is worth nothing. It does not get opened, does not drive clicks, does not generate revenue. It just sits in a folder that most people never look at.

Deliverability problems are more common than most US e-commerce brands realise — and more fixable. This guide covers everything you need to understand and improve your email deliverability, from domain authentication to list hygiene to sender reputation management.

Understanding How Deliverability Works

Before you can fix a deliverability problem, you need to understand the mechanics of how email providers (Gmail, Yahoo, Outlook, Apple Mail) decide whether your email lands in the inbox, the spam folder, or gets blocked entirely.

The decision is not binary or random. Inbox providers run sophisticated algorithms that evaluate:

Sender authentication: Has this email been sent from a legitimately authenticated domain? Or does it look spoofed?

Sender reputation: Does this sender have a history of sending email that recipients engage with? Or do they send to old, purchased, or unengaged lists?

Content signals: Does the email look like spam? Are there phishing indicators, excessive image-to-text ratio issues, or blacklisted URLs?

Engagement history: Do recipients from this sender typically open and click? Or do they delete without opening, mark as spam, or let emails pile up unread?

List quality signals: Is the sender mailing to valid addresses? Or are there high bounce rates, spam trap hits, and complaints?

Modern inbox providers — particularly Gmail, which handles a large proportion of US consumer email — weight engagement signals heavily. The best technical authentication in the world will not save you if you are consistently mailing to people who do not want your emails.

Step 1: Domain Authentication (Non-Negotiable)

If your emails are not properly authenticated, you are starting every send at a disadvantage. Authentication tells inbox providers that you are who you say you are.

SPF (Sender Policy Framework)

SPF is a DNS record that lists the servers authorised to send email on behalf of your domain. When an inbox provider receives an email from your domain, it checks whether it came from an authorised server. If not, that is a red flag.

Your ESP (Klaviyo, ActiveCampaign, Mailchimp, Omnisend, HubSpot, etc.) will provide SPF records to add to your DNS. This is usually a one-time setup. Do it.

DKIM (DomainKeys Identified Mail)

DKIM adds a digital signature to every email you send, verified against a public key stored in your DNS. It proves that the email content has not been altered in transit and that it genuinely originated from your domain.

Again, your ESP provides DKIM records. All major ESPs walk you through the setup process. This is essential.

DMARC (Domain-based Message Authentication, Reporting & Conformance)

DMARC tells inbox providers what to do when an email from your domain fails SPF or DKIM checks. Policy options range from “monitor only” (p=none) to “quarantine” to “reject.”

For US e-commerce brands, the recommended approach is:

Start with p=none to monitor authentication failures without affecting deliverability
Review DMARC reports to identify any legitimate sending sources not yet covered by SPF/DKIM
Move to p=quarantine or p=reject once you are confident all legitimate sending is authenticated

DMARC also protects you from domain spoofing — bad actors sending phishing emails that appear to come from your domain.

BIMI (Brand Indicators for Message Identification)

BIMI is a newer standard that displays your brand logo in the inbox next to authenticated emails. It requires a DMARC record at enforcement level (quarantine or reject) and a verified mark certificate. While not yet universal, it improves brand visibility and trust signals in supported inbox providers.

Step 2: Sending Domain Strategy

Many e-commerce brands make the mistake of sending all their email from their root domain (e.g., [email protected]). If your email programme ever develops a deliverability problem, it can affect your entire domain — including transactional emails and your website’s contact forms.

Best practice: Send marketing email from a subdomain (e.g., [email protected] or [email protected]). This isolates your marketing reputation from your root domain reputation.

This is a standard setup on all major ESPs. When you configure your sending domain in Klaviyo, ActiveCampaign, or any other platform, use a subdomain.

Step 3: Domain and IP Warming

When you start sending from a new domain (or a new subdomain) or switch to a new IP address, inbox providers have no reputation data for you. You are unknown — and unknown is treated with caution.

Domain and IP warming is the process of gradually increasing your sending volume to establish a positive sending history.

Warming Protocol

Do not start by sending your full list on Day 1. Instead:

Week 1: Send only to your most engaged subscribers — people who have opened or clicked in the last 30–60 days. Volume: 500–1,000 emails per day.

Week 2: Expand to 60–90 day openers. Volume: 2,000–5,000 per day.

Week 3: Expand to 90–180 day openers. Volume: 10,000–20,000 per day.

Week 4: Begin including all engaged subscribers. Volume: 25,000–50,000 per day.

Weeks 5–8: Gradually approach full list volume.

Throughout this process, monitor:

Open rates (should stay above 20%+ during warmup)
Spam complaint rates (should stay below 0.1%)
Bounce rates (should stay below 2%)
Inbox placement in Gmail, Yahoo, and Outlook

If any metric spikes negatively, slow down the ramp-up.

Why This Matters for Brands Switching ESPs

If you are migrating from Mailchimp to Klaviyo, or from any platform to another, you are warming a new sending configuration. Do not blast your full list on migration day. Follow a warming protocol. Many brands experience temporary deliverability dips post-migration that could be avoided with proper warm-up planning.

Step 4: List Hygiene

Your list quality is perhaps the single most important deliverability factor after authentication. Sending to bad addresses, inactive subscribers, and spam traps will tank your sender reputation.

Remove Hard Bounces Immediately

A hard bounce means the email address does not exist or is permanently unavailable. Every major ESP should automatically suppress hard bounces, but verify that this is happening in your account.

Hard bounce rates above 2% are a red flag for inbox providers.

Manage Soft Bounces

Soft bounces (full inbox, temporary server issue) can become hard bounces. After 3–5 consecutive soft bounces to the same address, suppress it.

Suppress Long-Term Non-Openers

This is the most impactful and most resisted hygiene practice. If a subscriber has not opened a single email in 6–12 months, they are hurting your engagement metrics and your sender reputation.

Do not keep them on your active list indefinitely. Run a sunset flow (3 emails asking them to confirm they still want to hear from you), then suppress non-responders.

Yes, your list will shrink. No, that is not a bad thing. A smaller, engaged list consistently outperforms a large, unengaged one on every metric that matters — including revenue.

Never Buy Email Lists

Purchased lists are one of the fastest ways to destroy a sender reputation. They contain spam traps (email addresses set up specifically to identify spammers), uninterested recipients (near-certain complaint generators), and outdated addresses (high bounce rates). There is no scenario in which a purchased list is worth the deliverability damage.

Use Double Opt-In for New Subscribers

Double opt-in (requiring a confirmation click after signup) adds friction to your signup process but produces a cleaner, more engaged list. Confirmed subscribers are more likely to open, less likely to complain, and produce better deliverability signals.

For US brands, double opt-in is not legally required under CAN-SPAM (unlike in some other jurisdictions), but it is best practice from a deliverability standpoint.

Step 5: Engagement-Based Sending Segmentation

One of the most powerful deliverability strategies is adjusting your sending approach based on engagement level.

Divide your list into engagement tiers:

Active (opened/clicked in last 30 days): Send everything. Full frequency. These are your best reputation signals.

Engaged (opened/clicked in 31–90 days): Send most campaigns. Full frequency but monitor closely.

At risk (opened/clicked in 91–180 days): Reduce frequency. Send only your strongest campaigns. Run a re-engagement sequence.

Lapsed (no engagement in 181–365 days): Minimal sending. Re-engagement sequence only.

Inactive (no engagement in 365+ days): Sunset flow, then suppress.

When you need to send a high-volume campaign (like a Black Friday send), always lead with your most engaged segments. Let the positive engagement signals from active subscribers build momentum before reaching out to less engaged contacts.

Step 6: Content and Technical Signals

Your email content affects deliverability. Inbox filters look at both the technical construction of your email and its content.

HTML Quality

Poorly structured HTML — excessive nesting, table-within-table constructions, inline CSS errors, and broken tags — can trigger spam filters. Use your ESP’s tested templates rather than custom HTML you have not verified.

Image-to-Text Ratio

Emails that are 90% images and 10% text look suspicious to spam filters. They also fail to render for recipients who have images turned off (still a meaningful minority). Aim for a balanced ratio, and always include meaningful alt text on images.

Links

Every link in your email should point to a live, reputable domain. Never link to domains that have been blacklisted. Avoid URL shorteners in email (they are associated with phishing). Use your brand domain in links where possible.

Spam Trigger Words

While modern spam filtering is far more sophisticated than simple keyword matching, certain patterns still raise red flags: excessive use of “FREE,” “WINNER,” “GUARANTEED,” “CLICK NOW,” excessive punctuation, and all-caps subject lines. Write naturally and these are not a concern.

Unsubscribe Link

Every commercial email must contain a functional unsubscribe link under CAN-SPAM. Beyond legal compliance, making your unsubscribe easy is good deliverability practice. A frustrated subscriber who cannot unsubscribe hits “Report Spam” instead — a far worse outcome for your sender reputation.

Step 7: Monitor Your Sender Reputation

You cannot manage what you do not measure. Use these tools to monitor your deliverability:

Google Postmaster Tools: Free tool from Google that shows your domain reputation and IP reputation for Gmail deliveries. If you are sending at meaningful volume to Gmail addresses, set this up immediately.

Yahoo/Verizon Postmaster: Similar tool for Yahoo Mail deliveries.

MxToolbox: Checks whether your domain or IP is on any major email blacklists.

Sender Score (Validity): Assigns a numeric reputation score to your sending IP address. Scores above 80 are good; below 70 is concerning.

EmailOnAcid or Litmus: Email testing tools that include spam filter checks alongside inbox rendering previews.

Your ESP’s deliverability metrics: Open rates, bounce rates, spam complaint rates within your ESP are your first-line indicators. Set up alerts for unusual spikes.

Step 8: Handling a Deliverability Crisis

If you notice a sudden drop in open rates, high bounce rates, or spam complaints, take these steps immediately:

Stop sending to the full list. Pause all campaigns and flows to non-engaged subscribers.
Check blacklists. Use MxToolbox to see if your domain or IP is listed.
Check Google Postmaster. Look for reputation drops in the Google dashboard.
Audit recent campaigns. What changed? Did you send to an older segment, use a new template, include a new link, or significantly increase volume?
Send only to engaged subscribers while you diagnose and fix.
Contact your ESP support. They have deliverability teams that can assist with diagnosis and remediation.
If blacklisted, submit removal requests to the relevant blacklist operators after addressing the root cause.

Recovery time varies: some issues resolve in days; others take weeks. The faster you catch and respond, the faster you recover.

CAN-SPAM Compliance Recap

For US e-commerce brands, CAN-SPAM requires:

Honest subject lines and “From” names: No deceptive headers
Physical mailing address: Must appear in every commercial email
Clear unsubscribe mechanism: Must be easy to find and functional
10-day unsubscribe processing: Opt-outs must be honoured within 10 business days
Identification as advertising: Commercial emails must be identifiable as such where not obvious

Every major ESP handles these requirements through standard footer and compliance features. Use them.

Experiencing deliverability problems or worried about where your emails are landing? Excelohunt provides full-service email deliverability audits and remediation for US e-commerce brands on Klaviyo, ActiveCampaign, Omnisend, HubSpot, Mailchimp, and all major ESPs.

Book your free email audit — we will tell you exactly where your deliverability stands and what needs to change to get your emails into inboxes and your revenue back on track.