You Do Not Have an Email Problem You Can Fix With SMS

Adding SMS marketing to a broken email program does not double your revenue. It doubles your ways to annoy people.

Klaviyo wants to be your CRM. Not your email tool, your full B2C CRM: email, SMS, WhatsApp, RCS, push, all one stack, one login, one bill. That’s a smart move for Klaviyo. It isn’t automatically a smart move for you.

A channel isn’t a revenue line. It’s a multiplier on whatever program you already have.

If your flows convert, a new channel gives you more surface area to convert on. If your flows don’t convert, a new channel gives you more surface area to fail on, at a higher cost per send.

So before you turn on SMS marketing, ask what it’s actually multiplying.

If your welcome flow is generic, SMS marketing won’t fix that. It’ll just text people the same generic message you were already emailing them, faster and at a higher cost per send.

If your abandoned cart flow has one email and no urgency, adding a text to that sequence doesn’t create urgency. It creates two channels with nothing worth saying.

If your offer isn’t compelling, no channel fixes an offer problem. You’ll just be underperforming in more inboxes at once.

The number that sells SMS marketing is the open rate. You have seen it: somewhere north of 90%, usually presented next to email’s 20-something percent, and the gap is meant to end the conversation.

Klaviyo does not track it.

That’s not a gap in their reporting. It’s stated outright in their documentation on SMS metrics: “Klaviyo does not track open rates for SMS, because most recipients will open an SMS message that they receive.”

Read the reason again. It’s an assumption about behavior, not a measurement of it.

The metrics Klaviyo does record for SMS are delivery-side and click-side: Relayed, Received, Failed to Deliver, Clicked, Subscribed, Unsubscribed. Open isn’t among them, and Klaviyo scopes open rate to email and push only.

There’s a mechanical reason. Email open tracking works because the message loads a tracking pixel, and that request is the “open.” A text message has nothing to load and no request to fire. There’s no pixel, so there’s no open.

Where a 90-something percent figure is defined at all, it’s inferred from delivery, and it counts a message appearing on a lock screen. A glance at a notification isn’t a read, and it certainly isn’t a comparison to an email open.

None of this means SMS marketing doesn’t work. It means the single number most often used to justify ecommerce SMS marketing isn’t measuring what the pitch implies, and if that number is doing the persuading in your internal business case, the case is thinner than it looks. Compare click rate and conversion rate across channels instead. Both are real, and both are in your dashboard.

Klaviyo’s own pricing tells you which channel is expensive to deliver, without anyone needing to quote a per-message SMS marketing rate.

On the free tier, Klaviyo grants you “500 emails/month” and “$5 of mobile messages/month.”

Email is allocated by count. SMS marketing is metered in dollars. Vendors meter in dollars what costs them money to send, and they hand out by the hundred what doesn’t.

That asymmetry follows you onto paid plans as a separate line on the bill. Email pricing scales with the size of your list. SMS spends down a balance every time you hit send, which means an SMS marketing program has a variable cost that a generic message doesn’t earn back.

The practical consequence is that SMS marketing punishes low-quality sends in a way email doesn’t. A mediocre email costs you almost nothing to send and a little goodwill. A mediocre text costs you money on the way out and a subscriber on the way back.

Email has a forgiving failure mode that SMS marketing does not. People ignore you, drift, and stop opening, and you can re-engage them later or let a sunset flow retire them quietly. Nothing is permanent.

SMS marketing doesn’t work like that, and the difference is legal rather than cultural.

Under FCC rules that took effect on April 11, 2025, a consumer can revoke consent to marketing texts “in any reasonable manner,” and senders “may not infringe on that right by designating an exclusive means to revoke consent that precludes the use of any other reasonable method.”

So they don’t have to text STOP. They can reply in words, tell you on a call, or use any other reasonable route, and it counts.

You then have to honor it “as soon as practicable and no more than 10 business days after receipt.” After that you’re allowed exactly one confirmation text, and it can’t carry any marketing or promotional content.

That’s the whole relationship. One clean exit, honored by any method they pick, with a receipt and nothing else. People opt into SMS expecting relevance and urgency. Get it wrong twice and they’re gone for good, no warning and no second chance, and the law is on their side.

Set the two channels side by side on the axes that actually govern a program, rather than on the one number the pitch leads with. Everything in this table is a structural difference, not a preference.

Read down the SMS column and the pattern is consistent. Every row is less measurable, less forgiving, or more expensive than its email counterpart. That’s not an argument against SMS marketing. It’s an argument that SMS marketing is a channel you earn your way into rather than one you switch on to fix something.

The fix is boring and it works.

Before you price SMS marketing, audit your core email flows: welcome, abandoned cart, post-purchase, win-back. Look at click rate and conversion rate for each, and find where the message is weak rather than where the channel is weak.

We ranked those flows by what each one actually returns in the best Klaviyo flows to build, and the ranking is not the order most brands are sold. Start there before you price a second channel, because the gap between an average flow and a good one is larger than anything a new channel adds on top.

Then fix the copy, fix the offer, fix the timing. Get those flows converting the way they should on the channel you’re already paying for.

If the flows are fine and the offer is the problem, that’s a different diagnosis, and it’s the one a conversion rate optimization audit exists to answer with your own numbers.

Once a flow is proven and profitable on email, that’s your signal that SMS marketing has something worth carrying.

You have a message worth paying more to deliver faster or in a second inbox. That’s when SMS marketing earns its cost per send. Not before.

The test for adding SMS marketing is specific. A flow qualifies for SMS marketing when it converts on email, when the message is genuinely time-sensitive, and when the thing you’re texting couldn’t have waited for an inbox. Cart recovery, shipping updates, a real drop with a real deadline. Those pass.

A monthly newsletter does not. Neither does a second copy of a welcome email.

Omnichannel is a reward for a program that already works, not a repair kit for one that doesn’t.

Fix the flows. Fix the offer. Then decide if you need a second channel, and let the data tell you which one.

If you’d rather have someone audit the flows first and tell you honestly whether SMS is your next move or your next distraction, that’s where our email and SMS marketing work starts.