(And How to Fix Them)
Last updated October 2026 by Lily Newman
These are the five email mistakes that cost ecommerce brands the most, in the order I would fix them: sending everything to everyone, judging by opens, skipping authentication, running on campaigns alone, and discounting by default. Each has a fix you can start this week.
1. Sending every campaign to the whole list
What it looks like: One promotion, one send, 100% of subscribers.
Why it costs you: Unengaged subscribers increase your risks of deliverability issues by driving up your complaint rate and unsubscribe rate. Email providers like Google advise bulk senders to keep the spam rate in Postmaster Tools under 0.10% and to never reach 0.30% (Google). Once your emails start falling into spam folders, it can be tricky to navigate your way back out. Plus, by sending to unengaged subscribers, you are throwing away money on campaigns that likely won’t earn back an ROI.
The fix: Create engagement-based segments filtered by recency of engagement (at a minimum looking at purchase history, site activity, and email open/click activity). Send your strongest content to the broadest expression of your engaged segments. Send less compelling content to tighter, warmer segments. Stop emailing people who have ignored every message for a long stretch (after giving them the opportunity to re-engage with a final "still want these?" message first). Note that "Long" depends on your category, so set it from your own reorder or engagement cycle, however for most brands a safe rule of thumb is to filter out subscribers that have received at least 10 emails within the last 90 days and that opened (excluding Apple Privacy - see below) or clicked a campaign zero times in that timeframe.
2. Judging performance by open rate alone
What it looks like: Subject line tests decided on opens, and reports that lead with open rate.
Why it costs you: Apple Mail Privacy Protection can pre-load messages, so opens are inflated. Apple devices account for 62.26% of opens in Litmus's July 2026 client report (Litmus), which means a large share of your open data is unreliable.
The fix: Judge campaign performance on clicks, placed order rate, and revenue per recipient (RPR). Look at opens as a secondary metric, using a tool like Klaviyo that lets you filter out Apple Privacy Opens (Klaviyo). If you test subject lines, pick the winner on clicks or revenue. The deliverability guide covers this in more detail.
3. Skipping authentication and one-click unsubscribe
What it looks like: Email campaigns go out, the open rate starts drifting down, and nobody knows why.
Why it costs you: Gmail and Yahoo now require authentication and easy unsubscribes, and the penalties are placement, not fines. Bulk senders need SPF, DKIM, DMARC, and a one-click unsubscribe, and all senders need at least basic authentication.
The fix: Run the six-step audit in the deliverability guide. It takes an afternoon and protects every send after it.
4. Running on campaigns alone
What it looks like: A busy send calendar and no flows, or flows nobody has touched in years.
Why it costs you: According to Klaviyo's 2026 benchmarks, behaviorally-triggered flows and automations contribute on average about 5.3% of email sends and about 41% of email revenue for e-commerce brands, with a 5.58% click rate against 1.69% for campaigns (Klaviyo). That’s an outsized revenue contribution on a comparatively small amount of sends, meaning if you’re not covering your bases with flows you’re missing out on a lot of potential dollars.
The fix: Build or rebuild three priority flows immediately: welcome, abandoned checkout, and post-purchase. Fill in the rest (abandoned cart, browse, winback, and more) when you can. The campaigns vs flows guide has the order.
5. Discounting by default
What it looks like: A percentage off in most sends, because it works.
Why it costs you: It works until customers learn to wait for it. You also pay for the discount on orders that would have happened anyway.
The fix: Give each discount a job: first order, winback, or clearing stock. For everything else, test a different reason to buy, such as early access, a restock, a how-to, or a new product story. Abandonment flows are often treated with a discount code at the first touch. Consider delaying for a second touchpoint or testing no offer at all to see if you can move the needle.
Quick checks before every send
Preview on an iPhone and in the Gmail app. A majority share of your subscribers will see it there
Click every link and confirm the offer, dates, and prices
Confirm the unsubscribe link works and the sender name is one customers recognize
Include alt text on images, and make sure the message still makes sense with images off
Frequently asked questions
How often should I send marketing emails? There is no universal number. Start with a cadence you can keep, then watch unsubscribe rate, complaint rate, and revenue per recipient. If those climb together, you are sending too much.
What is a good open rate? Because of Apple's pre-loading, open rate is no longer a reliable measure. Use click rate and revenue per recipient.
Should I buy an email list? No. People who never signed up complain, and complaints damage deliverability for your whole program.
What is a good unsubscribe rate? While it varies by category and cadence, most retail brands see an unsubscribe rate between 0.1% and 0.5%. Track your own trend, and treat a sudden jump as a sign to check what changed.
Want a second set of eyes on your email program? Talk to Newly Marketing.
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About the Author
Lily Newman is the Founder and Principal of Newly Marketing, a digital marketing consultancy specializing in lifecycle, email, mobile, CRM, and retention marketing. A fractional DTC e-commerce marketing leader, Lily advises high-growth startups and Fortune 500 brands in retail, CPG, health and wellness, and technology, drawing on 15+ years leading acquisition and retention for Levi's, Peet's Coffee, Mighty Leaf Tea, Four Sigmatic Foods, and more.
