SMS vs Email Marketing in 2026: Two Channels, Two Billing Units

SMS vs email marketing is a choice between two billing units as much as two channels. Email is bought as a plan sized by contacts and monthly sends, so a longer email costs nothing extra. A text is billed per segment: 160 characters fit in one, and one emoji or curly quote can cut every segment to 70.

That last rule turns the words of a text into a line item. Klaviyo’s help center says special characters “shorten the message’s character limit from 160 to 70” and that “the 70-character limit applies to every message segment for that SMS.” Its list of special characters includes the curly double quotation mark, and it warns that the problem “is a common issue if you’re copying text and symbols from a third party.” So a 150-character text pasted from a polished email draft can bill as three segments instead of one, for the same words. Klaviyo adds that such lookalike characters usually change to plain ones before delivery, but “this is not always the case”. Email has no equivalent: Klaviyo’s and Mailchimp’s email meters count contacts and sends, and neither has a term for length or character set. This guide reads Klaviyo’s, Mailchimp’s, Postscript’s and Attentive’s own pages as served on October 15, 2026. It is published by Relvino, which decides per shopper across email, SMS and pop-ups and so has a stake in how brands split the two channels; read it as informed but interested.

How email is billed: a plan sized by the list

Klaviyo’s billing article describes its email product in two meters. Profile and Email plans are based on the number of active profiles in the account and on “Emails sent during the current billing cycle”. How those sends are spread is the brand’s business: “Your emails can be to any of your active profiles”, the article says, and a brand can “send more to certain groups and less to others (e.g., 100 to group A, and 1 to group B).” Some sends do not count at all: “Double opt-in (confirmation) emails don't count toward your email send usage, regardless of your plan.” Paid tier prices sit inside an interactive plan builder on the pricing page, so they are not quoted here; the free plan, in the page’s text, is “Up to 250 active profiles” and “500 email sends/month”.

Mailchimp’s pricing grid states the send allowance as a multiple of the list. Monthly email sends are ten times the contact count on Essentials, twelve times on Standard and fifteen times on Premium; the Free plan is listed at “Max of 500/mo or 250/day”. Past the allowance on a paid plan, the FAQ says “Mailchimp will automatically bill you for your overages.”

The shape that follows is a step, not a slope. Inside the allowance, the next email is already paid for. At the edge, the brand buys more: an overage at Mailchimp, or at Klaviyo an upgrade or a flex purchase, which Klaviyo describes as “a one-time purchase that includes all of the capacity units in the next tier (i.e. # of email sends) at the unit rate (cost per send) of your current plan.” Nowhere in either meter does the length of the email, the number of images or the typography change what one send costs.

How SMS is billed: a price per segment

Text is metered per message, and the message is not the unit the shopper sees. Klaviyo sells Mobile Messaging as a separate monthly plan bought in dollars upfront, and “The plan resets monthly and unused dollars do not carry over.” Each send draws down that balance at a rate: “Your rate is the dollar price of a single message.” The billing article lists what sets the rate: channel, country or region, number type for US and Canada SMS, carrier and provider costs (“Built into the rate.”) and the number of message segments. On segments it is explicit: “SMS has a limit of 160 characters normally, but only 70 characters when there's an emoji or special character.” A longer text is split, and “When a text contains multiple message segments, it still shows a single message on the recipient’s phone.” The shopper reads one message; the invoice counts three.

Postscript publishes its rates. On the Growth plan, at $100 a month, the pricing page lists “$0.008/SMS, $0.03/MMS + Carrier fees*”, with the footnote “Average US Carrier fees. SMS: $0.00330.” Its FAQ states the segment rule in terms of emojis, 160 characters without and 70 with: messages over the limit “are split into multiple message segments, each of which is charged at the per-SMS rate”, while an MMS carries up to 1,600 characters with or without emojis. Postscript bills differently in two other ways it states itself: “Pay after you send” and “Zero profile fees - we don’t punish you for growing your list.”

Mailchimp sells texting only beside a paid plan. Its FAQ says “SMS marketing is available to Mailchimp users in select markets with a paid marketing plan”, after an application and approval, with credits bought in monthly blocks, and “Unused credits will expire each month and do not roll over.” Attentive publishes no rates; its Text bundle reads “Pay per message and subscriber count”, and the detail of what that page does and does not say is in the Attentive pricing guide.

What one curly quote costs

Take a cart reminder of 150 characters, written in plain letters, digits and straight punctuation. It fits in one segment. Now add one emoji, the case Postscript’s own segment rule names, or paste in a curly quotation mark that the platform fails to convert. The whole message switches to the 70-character limit, and 150 characters need three segments, because Klaviyo says a two-part special-character text, with the header that joins the parts, holds 134 characters.

At Postscript’s Growth rate plus its stated average carrier fee, applied to each segment (an assumption, since the page gives the fee per SMS and does not say how it applies to a split message), a segment costs about $0.0113. Sent to 10,000 subscribers, the plain version costs about $113 and the version with one emoji about $339. That is this guide’s arithmetic on Postscript’s published figures, and carrier fees vary by carrier, so treat it as an order of magnitude. The same reminder as an email, at 150 characters or 1,500, is one send against the plan’s allowance.

The same arithmetic shows where MMS becomes the cheaper format. On Growth, an MMS at $0.03 plus the stated average MMS carrier fee of $0.00799 costs about $0.038, against about $0.034 for a three-segment SMS and about $0.045 for four segments. On those averages, a text that runs to four segments or more costs less sent as MMS, which also allows an image.

Klaviyo’s exact rates appear only inside an account, so they cannot be set beside Postscript’s here, and the full billing rules for its SMS plan, carrier fees included, are in the Klaviyo SMS marketing guide.

SMS vs email marketing at a glance

Quoted phrases are from each vendor’s own pricing page or help center; every other cell is this guide’s summary of those pages.

• Klaviyo · Email is billed on: Active profiles and “Emails sent during the current billing cycle” · SMS is billed on: “the dollar price of a single message”, set by channel, region, number type and segments · Carrier fees on SMS: “Built into the rate.” · Unused SMS spend: “unused dollars do not carry over”
• Mailchimp · Email is billed on: Contacts, with monthly sends of ten, twelve or fifteen times the contact count by plan · SMS is billed on: Monthly credit blocks on a paid plan, in select markets, after approval · Carrier fees on SMS: Not stated on the pricing page · Unused SMS spend: “Unused credits will expire each month and do not roll over.”
• Postscript · Email is billed on: No email price published; the pricing page offers a waitlist · SMS is billed on: Per segment, $0.009 to $0.007 per SMS by plan · Carrier fees on SMS: Added on top; stated US average $0.00330 per SMS · Unused SMS spend: Billed after sending, no prepaid balance
• Attentive · Email is billed on: Text and email bundle: “Pricing based on list size and messages sent” · SMS is billed on: “Pay per message and subscriber count” · Carrier fees on SMS: Not stated · Unused SMS spend: Not stated

Is SMS marketing better than email marketing?

Neither channel wins on every message, and the billing units explain much of why. A text is short, priced per segment and read on the phone, so it suits a message whose whole value fits in one segment: a restock in the size a shopper wanted, the last hours of a sale, a delivery problem that needs a reply. An email carries images, product grids, sizing tables and a story at one price per send, so it suits anything that needs explaining or browsing. A brand that sends the same long message to both channels pays twice and gets the cheap channel’s strengths in neither.

Consent is the other boundary. The two lists are built separately and governed by different rules, which the SMS marketing best practices guide covers from the statutes and carrier codes themselves; this guide does not restate them, and nothing here is legal advice. The economic point is narrower: every text spends money and some of the shopper’s patience with a channel that sits beside personal messages, so the bar for sending one should be higher than the bar for an email.

Using both channels without paying twice for one message

The expensive overlap is the shopper who receives the cart email and, an hour later, the cart text with the same offer. When the two sends are scheduled by separate rules, the overlap is easy to miss, and in Klaviyo even the frequency limit is split: its text message settings article says “SMS Smart Sending and email Smart Sending are treated separately.” The text was the priced one, and it may have reached a shopper the email had already persuaded.

The useful question is therefore asked per message, not per calendar: for this shopper, now, does this content justify a priced text, or will an email at no extra metered cost do the same job? Relvino makes that call per shopper across email, SMS and pop-ups, inside the channels and limits the brand sets. Whatever system makes it, the inputs are the ones above: what the message has to carry, how long it is once encoded, and which list the shopper is on.

What to ask before choosing an email and SMS platform

The pages above suggest five questions that sort platforms faster than feature lists do. Each comes from a difference the vendors above describe in their own words.

• Is the SMS rate all-in? Klaviyo builds carrier fees into its rate; Postscript adds them. Compare like with like before comparing numbers.
• Prepaid or billed after? Klaviyo’s dollars and Mailchimp’s credits expire monthly; Postscript bills after sending. A prepaid plan sized for a peak month wastes money in a quiet one.
• Does the list itself cost money? Attentive prices on subscriber count, Postscript says zero profile fees, and Klaviyo’s email plan is sized by active profiles.
• Does the editor show encoding and segment count before sending? A curly quote should be caught in the editor, not on the invoice.
• What happens at the email allowance? Overage, flex purchase or a forced tier change each cost differently in a heavy month.

For SMS-first vendors specifically, the Postscript vs Attentive comparison reads both companies’ pages side by side.

Where the two units leave a brand

The two channels reward opposite writing. In email the copy can run as long as the argument needs, because the meter counts sends, not words. In SMS every character past the limit is a purchase, and a single typographic flourish, a curly quote or a heart, can triple the cost of a send without changing what it says. A sound split treats a text as a priced, one-segment decision and an email as the place where the explaining happens, and decides which one a shopper gets before either is written.

Frequently asked questions

Is SMS getting phased out?

Not on the vendor pages read for this guide. They are adding RCS, the richer messaging standard, beside SMS and pricing it per message too. Klaviyo’s rate table lists SMS, MMS, WhatsApp and RCS as channels on one Mobile Messaging plan, and its RCS article says it does not currently charge any RCS agent fees in any country, while noting fees may be introduced for agents registered in the US. Postscript states a separate average carrier fee for a text RCS message, $0.0047 against $0.00330 for an SMS, and lists RCS as an option on its Enterprise plan.

Is SMS marketing better than email marketing?

It depends on the message, and on costs that only one of the two channels has. Klaviyo’s billing article says skipped and inbound messages do not cost anything but failed deliveries do, so a text list full of disconnected numbers shows up on the invoice. Sender numbers can cost money too: Postscript assigns a toll-free number free and says a dedicated short code, which it suggests for high volume or fast, consistent delivery, costs $750 a month through the carriers, passed through without markup.

What is the best email and SMS marketing platform?

There is no single answer, and this guide is published by Relvino, which competes for the same budget. Vendor-neutral tests: whether email and SMS can be bought and dropped separately (Klaviyo’s billing article says a brand can stop paying for Mobile Messaging while keeping its email plan), and whether texting can be tried before committing (Postscript says its free trial carries a $100 credit for the first 30 days, applied to message and carrier fees).

Can you give me an example of SMS marketing?

A restock alert is the classic case: BRAND: The Linen Overshirt is back in size M, 6 left. Free returns as always. Shop now: brand.co/m Reply STOP to opt out. That is 120 characters, all plain letters, digits and straight punctuation, so it fits one 160-character segment. It names one product, one size and one link, and the opt-out line alone takes 21 characters, which leaves the rest of the story to email.

How much does SMS marketing cost compared to email?

At the entry level the vendors set the two channels very differently. Klaviyo’s free plan includes 500 email sends a month and $5 of mobile messages a month. Mailchimp’s Free plan includes no SMS at all, since texting needs a paid plan. Postscript’s Starter plan has no monthly fee but a $49 monthly minimum spend, at $0.009 per SMS plus carrier fees. So a brand can test email free on several platforms, while texting beyond Klaviyo’s $5 monthly allowance starts with a per-message bill.

How long does it take to migrate email and SMS to Relvino?

The technical cutover takes about 30 minutes: connect the Shopify store, point the sending domain and SMS number, and shopper data ingests automatically, with no flows to rebuild. Revenue is then measured in a 14-day pilot. Klaviyo’s billing article says that when Mobile Messaging is removed, the flows themselves remain in the account and can be edited or left paused, so a brand can wait for the pilot’s result before changing its old SMS plan.