SMS vs Email Marketing for E-Commerce: When to Use Each (And How to Combine Them)

The “SMS vs email” debate is a false choice. It’s like asking whether you should use your right hand or your left. The answer is both — but for different things, at different times, in different contexts.

That said, most e-commerce brands either over-invest in email and ignore SMS, or jump into SMS without a strategy and blow through their budget sending texts that should have been emails. Understanding when to use each channel — and how to orchestrate them together — is worth a 15-30% lift in total owned-channel revenue.

We manage both email and SMS programs for our clients through Klaviyo’s unified platform. Here’s what the data actually shows.

Key Takeaways

SMS has a 98% open rate and 36% click-through rate, but costs 5-10x more per message than email
Email drives more total revenue due to volume and lower cost per send
SMS excels at urgency: flash sales, restock alerts, limited-time offers, and cart recovery
Email excels at education, storytelling, product launches, and nurturing
Combined SMS + email flows generate 25-30% more revenue than email-only flows
The optimal SMS frequency is 4-6 messages per month; more than 8 drives unsubscribes

The Numbers: SMS vs Email Performance

Let’s start with raw performance data from our client accounts (aggregate across 100+ e-commerce brands):

Metric	Email	SMS
Open rate	22-28%	95-98%
Click-through rate	2.5-3.5%	20-36%
Conversion rate (click to purchase)	3-5%	8-12%
Revenue per recipient (campaigns)	$0.08-$0.15	$0.15-$0.30
Revenue per recipient (flows)	$0.50-$2.00	$0.80-$3.00
Cost per message	$0.001-$0.003	$0.01-$0.03
Unsubscribe rate per message	0.1-0.2%	0.5-1.0%

SMS wins on engagement rates across the board. The catch is cost and tolerance. Sending 12 emails per month is perfectly acceptable. Sending 12 SMS messages per month will get you unsubscribed faster than you can say “STOP.”

Revenue Attribution

Across our client portfolio, here’s how owned-channel revenue typically breaks down for brands running both email and SMS:

Email flows: 35-40% of owned-channel revenue
Email campaigns: 30-35%
SMS flows: 15-20%
SMS campaigns: 10-15%

Email still drives the majority of revenue because you can send more of it. But SMS punches above its weight — generating 25-35% of owned-channel revenue from only 15-20% of total messages sent.

When to Use Email

Email is your workhorse channel. It handles the heavy lifting of customer relationships: education, nurture, brand building, and detailed product storytelling.

Email Is Better For:

Long-form content. Product launches with multiple images, ingredient stories, brand narratives, lookbooks, recipe collections. SMS can’t do any of this. Email gives you a canvas.

Educational sequences. Post-purchase how-to guides, onboarding series, skincare routines, style tips. These require space and formatting that SMS doesn’t support.

Product catalogs and recommendations. Emails with dynamic product grids, personalized recommendations from Klaviyo’s AI engine, and visually rich layouts drive discovery. You can showcase 6-12 products in an email. SMS gets you one link.

Segmented campaigns to large audiences. When you’re emailing your full engaged list of 50,000 subscribers, the cost is $50-$150. The same SMS blast would cost $500-$1,500. Email’s economics make it ideal for broad-reach campaigns.

Re-engagement and winback. Multi-touch winback sequences work better as email because you need multiple messages over time, and the lower cost makes a 5-7 email sequence financially viable.

Newsletters and community building. Weekly roundups, curated content, brand updates — these belong in email where subscribers expect and welcome them.

When to Use SMS

SMS is your urgency channel. It cuts through noise in a way email simply cannot. When the inbox has 50 unread emails but the phone has 2 unread texts, SMS wins attention.

SMS Is Better For:

Flash sales and limited-time offers. “24-hour sale: 30% off everything. Shop now: [link].” SMS drives immediate action. Flash sale SMS messages generate 4-6x the revenue per message compared to flash sale emails because the read-and-act cycle is minutes, not hours.

Cart abandonment recovery. SMS cart reminders sent 1-2 hours after abandonment convert at 10-15% — nearly double the email equivalent. The immediacy of SMS matches the urgency of a time-sensitive cart.

Back-in-stock alerts. “The [Product] you’ve been waiting for is back. Grab it before it sells out: [link].” These are inherently urgent. SMS ensures the customer sees it before the item sells out again.

Shipping and delivery updates. Transactional SMS (order confirmed, shipped, delivered) have 98%+ open rates and build trust. They’re also a chance to include a subtle cross-sell or review request.

VIP and loyalty communications. “You’ve earned enough points for a free [product]. Redeem now: [link].” VIP members respond exceptionally well to SMS because it feels personal and exclusive.

Event-driven moments. Birthday offers, anniversary rewards, seasonal reminders. “Happy birthday! Here’s 20% off — just for you: [link].” These personal moments land better via text than email.

The Cross-Channel Strategy: How to Combine Them

The real revenue unlock is using email and SMS together in coordinated sequences. Here’s how to orchestrate them in Klaviyo.

Abandoned Cart: Email + SMS

The highest-performing abandoned cart flow uses both channels with specific timing:

SMS (1 hour after abandonment): Quick nudge. “Hey [Name], you left something in your cart. Finish your order: [link].” No discount.
Email (4 hours): Full cart reminder with product images, reviews, and benefits.
Email (24 hours): Address objections — shipping info, return policy, FAQ.
SMS (36 hours): Urgency + incentive. “Your cart’s about to expire. Use code SAVE10 for 10% off: [link].”
Email (48 hours): Final email with stronger incentive and social proof.

This sequence recovers 12-18% of abandoned carts, compared to 8-12% for email-only sequences. That’s a 30-50% improvement.

In Klaviyo, use Conditional Splits to check SMS consent before the SMS nodes. If the subscriber hasn’t opted into SMS, skip to the next email. Use Smart Send Time to optimize when each message lands.

Welcome Series: Email + SMS

SMS (Immediate): “Welcome to [Brand]! Your code is [CODE]. Shop now: [link].” Deliver the incentive fast via SMS.
Email (Immediate): Full welcome email with brand story, bestsellers, and the discount code.
Email (Day 2): Brand story and values.
SMS (Day 3): “Have you used your welcome discount yet? It expires in [X] days: [link].” Reminder nudge.
Email (Day 5): Social proof and product education.
Email (Day 8): Personalized product recommendations.
SMS (Day 12): “Last chance for your welcome offer! Expires tomorrow: [link].”

Post-Purchase: Email + SMS

SMS (Order confirmation): “Order confirmed! We’re packing [Product] now. Track it here: [link].”
Email (Order confirmation): Detailed order summary with cross-sell recommendations.
SMS (Shipped): “Your order is on its way! Track: [link].”
Email (3 days post-delivery): How-to guide for the product they bought.
SMS (14 days post-delivery): “Loving your [Product]? Leave a quick review: [link].”
Email (21 days post-delivery): Cross-sell based on their purchase.

SMS Compliance: What You Need to Know

SMS marketing has stricter compliance requirements than email. Get this wrong and you face fines up to $1,500 per message under TCPA.

Requirements

Explicit opt-in required. You cannot text someone who hasn’t specifically consented to SMS marketing. Email opt-in does not equal SMS opt-in.
Clear disclosure at opt-in. Subscribers must know the frequency and type of messages they’ll receive.
Easy opt-out. Every SMS must include a way to unsubscribe (reply STOP).
Quiet hours. Don’t send SMS before 8 AM or after 9 PM in the recipient’s local time zone. Klaviyo’s Quiet Hours feature handles this automatically.
Consent records. Keep records of when and how each subscriber opted in. Klaviyo tracks this natively.

Building Your SMS List

SMS opt-in rates are naturally lower than email. Expect 30-50% of email subscribers to also opt into SMS. To maximize SMS opt-in:

Add SMS as the third step on your email popup
Offer an additional incentive for SMS (“Get an extra 5% off when you opt into texts”)
Include SMS opt-in in your checkout flow
Run social campaigns specifically driving SMS signups

Budget Allocation: Email vs SMS

Here’s how to think about budget allocation:

For Stores Under $1M/Year

Allocate 80-85% of owned-channel budget to email
Allocate 15-20% to SMS
Focus SMS on flows (automated), minimize SMS campaigns
Email carries the bulk of revenue

For Stores $1M-$5M/Year

Allocate 70-75% to email
Allocate 25-30% to SMS
Add SMS campaigns for major sales events and product launches
Begin A/B testing SMS frequency and content

For Stores $5M+/Year

Allocate 60-65% to email
Allocate 35-40% to SMS
Full cross-channel orchestration across all flows and campaigns
Dedicate budget to SMS for VIP and loyalty programs
Test MMS (multimedia messages) for product launches

Measuring Cross-Channel Performance

Track these metrics monthly to evaluate your email + SMS program:

Email Metrics:

Revenue per recipient (campaigns): Target $0.10+
Revenue per recipient (flows): Target $1.00+
Deliverability rate: Target 95%+
List growth rate: Target 5%+ per month

SMS Metrics:

Revenue per message: Target $0.15+
Click-through rate: Target 15%+
Opt-out rate per message: Keep below 1%
SMS list as % of email list: Target 30%+

Combined Metrics:

Owned-channel revenue as % of total: Target 30-40%
Cross-channel flow lift (vs. email-only): Target 20-30% improvement
Cost per dollar of owned-channel revenue: Target $0.03-$0.08

Common Mistakes

Treating SMS like email. Sending long, multi-paragraph texts. SMS should be 160 characters or less. One message, one CTA, one link.

Sending too many SMS messages. More than 6-8 SMS per month causes list fatigue. Unlike email, where 12+ per month is normal, SMS tolerance is much lower.

Not segmenting SMS differently from email. Your SMS audience skews more engaged and higher-intent. Don’t send the same message on both channels simultaneously — stagger timing and vary the angle.

Ignoring quiet hours. Sending SMS at 6 AM or 11 PM is a fast track to unsubscribes and complaints. Always respect Klaviyo’s Quiet Hours settings.

Running SMS without email infrastructure. SMS should supplement email, not replace it. If your email program isn’t solid (welcome flow, cart abandonment, post-purchase), fix that first before adding SMS complexity.

The Bottom Line

Email and SMS aren’t competing channels. They’re complementary tools that, when orchestrated properly, create a communication system greater than the sum of its parts. Email handles the depth — education, storytelling, product showcases. SMS handles the urgency — time-sensitive offers, reminders, personal moments.

The brands generating the highest owned-channel revenue in 2025 aren’t choosing one over the other. They’re running both through Klaviyo’s unified platform, with coordinated flows, shared data, and intelligent timing that meets each subscriber on the right channel at the right moment.

Start with email. Add SMS to your highest-performing flows. Then expand to SMS campaigns for your biggest moments. That’s the path to maximizing owned-channel revenue.

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