SMS vs. Email for Ecommerce: The Real Numbers

"Should we invest more in SMS or email?"

It's the most common question we hear from Shopify brands evaluating their retention stack — and it's the wrong one. It frames the decision as a competition between two channels that do different jobs.

The brands getting the best results use both. Email handles some things well. SMS handles other things well. And when you stop arguing about the channel and start fixing the moment — the instant a customer is about to run out and needs to reorder — the math changes in ways neither channel can affect on its own.

Part of The Ecommerce Retention Playbook.

The better question: "which channel handles which job?" Here's what the data says.

The Numbers Side by Side

Before strategy, the raw performance data. These are industry averages across ecommerce brands — your numbers will vary based on list quality, category, and execution.

Metric	SMS	Email
Open rate	98%	20-25%
Average read time	3 minutes	6 hours
Conversion rate (campaigns)	0.12%	0.10-0.15%
Revenue per message (campaigns)	$0.16	$0.08-0.12
Revenue per message (automations)	$0.81	$0.15-0.25
Cost per message	$0.01-0.03	$0.001-0.003
Subscriber tolerance	4-8/month	12-20/month

A few things stand out.

On a pure campaign basis, SMS and email perform more similarly than most people expect. Conversion rates land in the same range. SMS has a slight edge on revenue per message, but it costs 10x more to send. Neither channel runs away with it on campaigns alone.

The gap opens with automations. SMS automations — cart recovery, reorder prompts, back-in-stock alerts — return $0.81 per message compared to $0.15-0.25 for email. A 3-4x advantage for SMS in automated flows.

And the part most comparisons skip: neither of these numbers reflects what happens when the message lands on a personalized reorder page instead of a generic checkout. We'll get to that.

Where Email Wins

Email remains the backbone of ecommerce retention for good reasons. Here's where it outperforms SMS.

Content and storytelling. Email gives you space — multiple images, rich formatting, brand design elements, long-form copy. If you're telling a brand story, explaining a product's origin, or building a narrative around a launch, email is the format. A text message tops out at 160 characters before splitting into segments. Email has no practical ceiling.

Education and onboarding. Welcome sequences, product how-tos, usage tips — the content that turns a first-time buyer into a repeat customer. These need room. A five-part welcome series can walk a new subscriber through your brand story, bestsellers, care instructions, and community in a way that five texts cannot. (More on why those first weeks decide retention in the first 45 days post-purchase.)

Review collection and UGC. "How was your order?" emails with star ratings, photo uploads, and rich response options are an established workflow. You can embed review widgets, show related products, and make the feedback process visual. Email wins here.

Lower cost at scale. Email costs roughly $0.001-0.003 per message. SMS runs $0.01-0.03 — a 10x difference. When you're sending 3-5 messages per week to a list of 50,000, that gap compounds. Email gives you more attempts for the same budget.

Subscriber tolerance. People expect frequent emails. Three to five per week is standard, and during launches or BFCM, daily sends are normal. Three to five texts per week feels aggressive. Most subscribers tolerate 4-8 SMS messages per month before opting out. Email gives you more frequency to work with.

Analytics depth. Heatmaps, scroll tracking, click maps, A/B testing across subject lines, preview text, send times, content blocks — email analytics is mature. You can test at a granularity SMS doesn't offer yet.

None of this is controversial. Email is a proven channel. If someone told you to shut down email and go all-in on SMS, ignore them.

Where SMS Wins

Email has blind spots. Those are where SMS excels.

Speed and urgency. The average text is read within 3 minutes. The average email sits in an inbox for 6 hours before it's opened — if it's opened at all. For a flash sale ending in 2 hours, a time-sensitive restock, or a reorder moment that closes when the customer runs out, email cannot match SMS.

Attention. A 98% open rate means nearly every subscriber sees the message. That number isn't inflated by auto-opens or preview pane tracking — people read their texts. Email open rates sit at 20-25%, and even those are inflated by Apple's Mail Privacy Protection. SMS gets your message seen.

Automated flows. SMS automations return $0.81 per message — 3-4x what email automations produce. Cart abandonment reminders land faster. Reorder prompts hit at the right moment. Back-in-stock notifications arrive when speed matters most. High open rates plus time-sensitivity make SMS automations outsized performers. (For which automated flows actually drive the revenue, see the 80/20 of retention flows.)

Cart recovery. Abandoned cart emails work. Abandoned cart texts work better and faster. A text arriving 30 minutes after someone leaves a cart catches them while they still remember what they wanted. An email arriving at the same time sits behind 14 other unread messages.

Reorder prompts. "Running low on your dark roast? Tap to reorder" converts better than an email with the same message. The immediacy and simplicity of SMS make replenishment a natural fit — especially when the tap lands on a page that already knows what the customer buys.

Two-way interaction. Email is broadcast. SMS is closer to conversation. When a customer can reply to a text — ask a question, confirm a delivery, give feedback — it creates engagement email can't replicate. Those signals tell you who's engaged, who's interested, who's ready to buy.

Where the Moment Changes the Math Entirely

Most SMS-vs-email comparisons get this wrong: they compare SMS-as-messaging to email-as-messaging. Both channels send a message, include a link, and hope the customer navigates to a generic checkout page. Under that model, the two channels perform similarly. The numbers above prove it.

But the message was never the bottleneck. The page it lands on is. A generic store homepage or product grid forces the customer to remember exactly what they bought, find it, set the quantity, and grind through checkout. Every step is a place where intent leaks out.

This is where reOtter changes the equation. reOtter is a replenishment engine that predicts when each customer is about to run out and fires the reorder moment into whichever channel you already use — email or SMS. Both point the customer to the same place: a dynamic reorder storefront, a personalized one-click reorder page pre-loaded with exactly what that customer buys, at the right quantity, with the discount your rules allow. No hunting. No rebuilding the cart. The customer lands on the page and confirms.

The numbers shift accordingly.

Standard SMS campaigns convert at 0.12%. A reorder moment timed to consumption — landing the customer on their own reorder storefront — converts at 5.5%, a 45x increase, driven by removing the friction between "I'm out" and "I reordered."

Revenue per message tells the same story. A typical SMS campaign generates $0.16 per message. A consumption-timed reorder moment generates $2.01. Twelve times more revenue per message, not because the copy is better, but because the page already knows the customer and the timing already matches their habit.

Here's the part that resolves the whole debate: this lift doesn't belong to SMS. It belongs to the moment and the storefront behind it. Send the same reorder moment by email and it points to the same dynamic reorder storefront. The channel is the delivery truck. The storefront is the cargo. Argue about the truck all you want — the cargo is what converts.

The Channel Pairing Playbook

If each channel has distinct strengths, what does the optimal pairing look like? Here's how brands with the best retention numbers divide the work.

Email handles:

• Welcome sequences and onboarding education
• Product storytelling, brand narrative, and content
• Review collection and UGC requests
• Newsletter and community-building content
• Broad promotional campaigns (sales, new arrivals, seasonal)

SMS handles:

• Time-sensitive alerts — back-in-stock, flash sales, limited-time offers
• Cart abandonment recovery
• Reorder and replenishment prompts
• Shipping and delivery updates
• Quick engagement — polls, preference collection, feedback

The reorder moment handles (via either channel):

• Reorder Reminders timed to when each customer is about to run out
• At Risk and Winback re-engagement for customers slipping past their usual cadence
• Subscription Bridge prompts that turn repeat one-time buyers into subscribers
• Cross-sell at the moment of reorder
• Any high-intent moment where speed-to-repurchase matters

The rule of thumb: email builds the relationship, SMS creates urgency, and the reorder moment — wherever it's delivered — closes the repurchase on a page built for that one customer.

Each layer feeds the others. Email educates subscribers about your brand and products. SMS surfaces the right product at the right moment. The dynamic reorder storefront lets them act on that moment without friction. Remove any layer and the system weakens. (If you're working with a tight budget, these low-cost retention tactics get the same effect cheaply.)

Getting the Frequency Right

The other question brands face: how often to use each channel. No universal answer, but there are guardrails. (For the data behind send cadence, see the email and SMS send-frequency guide.)

Email: 3-5 times per week. Standard for most ecommerce brands. During launches or BFCM, daily sends are fine. Subscribers expect regular communication. The key is mixing content types — don't send five promotional emails in a row.

SMS: 4-8 messages per month. Reserve texts for moments that earn the interruption — time-sensitive offers, real alerts, personalized prompts. Every text should feel like it deserves to be a text. If the content could wait 6 hours, it belongs in an email.

Reorder moments: on the customer's clock, not yours. Replenishment prompts aren't a fixed-schedule blast. They're utility — they arrive when the customer is actually about to run out, predicted per customer, not on a calendar. The merchant owns the timing rules; reOtter does the math on when each person hits empty. That's why they don't feel like marketing.

A quick test: does this sound like a text from a friend, or a marketing email with fewer words? If it reads like a compressed email — multiple paragraphs, formal tone, generic discount code — it belongs in email. If it reads like something a person would text you — short, direct, timely, personal — it belongs in SMS.

"Hey, you're about due for your dark roast. Tap to reorder your usual." That's a text.

"We're excited to announce the return of our beloved Ethiopian Yirgacheffe dark roast, sourced from the highlands of..." That's an email.

Stop Asking the Wrong Question

The SMS-vs-email debate is a distraction. Both channels have clear, data-backed strengths and clear limitations. The brands winning at ecommerce retention assign each channel the job it does best — then stop obsessing over the channel and start fixing the moment.

Email builds trust and tells stories. It educates, nurtures, and maintains the relationship over time. Cheap enough to use frequently, flexible enough to carry rich content.

SMS creates urgency and delivers time-sensitive value. It gets read immediately, cuts through inbox noise, and drives action on automated flows at 3-4x the return of email automations.

The reorder moment closes the repurchase — through whichever channel you already use. Fired on consumption timing and landed on a dynamic reorder storefront, it converts at 5.5% and generates $2.01 per message, because it removes the friction that limits both email and traditional SMS.

Two channels, one moment, one storefront. The brands that treat them as one system — rather than picking favorites — build replenishment programs that compound over time.

Join the waitlist.