Alium Research

Top complaints about SMS marketing platforms

SMS platforms — mostly Attentive and Postscript in these interviews, with Klaviyo SMS beside them — draw complaints about cost, getting data in, building flows, support, missing features and attribution that flatters the channel. They do not draw complaints about compliance. Six complaints, which platform draws which, and why buyers who complain mostly stay.

By Roy Dungo, Operations · Alium Research From hundreds of verified buyer interviews Interviews through October 2026 Updated October 22, 2026

Based on verified interviews with the retention and lifecycle leaders who run SMS programs, at DTC and enterprise brands. Buyers are anonymized before publication; vendor names and views are reported as given. No vendor paid to appear or could edit this page.

Ask buyers what frustrates them about their SMS platform and cost comes first — per-message and MMS charges, AI tools sold as extras, a bill that feels high against how much they send — though most accept it as the price of the channel. Below it sit getting custom data in and coordinating SMS with email and other channels, building flows and segments, support that varies from excellent to absent, features buyers are still waiting for, and attribution that credits SMS with more than buyers believe it earned. What stands out is what is missing: nobody here complains about compliance, which buyers praise instead. Most complainers stay because the channel performs; the moves described here combine cost, service, attribution or data concerns in different ways. Most of the evidence comes from Attentive and Postscript users; other SMS tools draw too few complaints here to rank. For the ratings and the pre-purchase view, see what SMS buyers wish they'd known.

7.8/10
Attentive's buyer rating — the platform with the most complaints here, and the one most often called the category leader.
7.8/10
Postscript's rating — praised for managed service; its complaints concentrate on cost and the interface.
Compliance
No compliance complaints are raised in these interviews; buyers instead praise their platforms' compliance support and do-not-call screening.
Which SMS platform earns which complaint A qualitative map from the interview corpus. A filled dot marks a complaint commonly raised by a platform's own users; a hollow dot marks one raised less often; a dash marks one its users did not raise. Attentive's users commonly raise cost, data and orchestration, support and missing features, and raise flows and attribution less often. Postscript's users commonly raise cost and flows and usability, raise data and support less often, and do not raise missing features or attribution. Attentive Postscript Cost and add-ons Data in, channels coordinated Flows, segments and usability Support and service level Features still missing Attribution that flatters SMS commonly raisedraised less oftennot raised
Where each platform's own users raise each complaint about SMS — a qualitative read, not a score; a complaint counts as common when roughly a fifth or more of that platform's complaining users raise it. Attentive rests on far more buyers than Postscript, whose column moves with a single company, and two of Attentive's cells sit right on the line. Klaviyo SMS and other SMS tools have too few complaining users here to chart.
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The six complaints — graded

Each complaint is classified by how buyers in these interviews typically respond: tolerating the issue, working around it, waiting for the vendor, or reconsidering the contract. These are observed responses, not fixed severity ratings; the same limitation may be manageable for one brand and unacceptable for another.

Complaint 01 Often tolerated — but part of several moves

Cost, and the extras on top

The most common complaint, and most buyers accept it as the nature of the channel: “I would say it's one of our more expensive vendors, but SMS messaging is just expensive,” says one Attentive user. Others feel the fixed fee outweighs their volume — “The monthly fee is high compared to how little SMS we are sending monthly” — or object to paying separately for AI, wanting “more of their AI tools built into our contract versus everything being an extra charge.” On Klaviyo SMS, one team has “to be very mindful of our credits, which I think is more of an industry issue.” Cost alone rarely drives a move — “But SMS marketing is a must, so we stay with Attentive,” one buyer says — but it features in several of the replacement decisions described here, where buyers also cite service expectations, attribution concerns or data limitations.

Named for this: Attentive · Postscript · Klaviyo SMS

Complaint 02 Puts the contract in play

Getting data in, and coordinating SMS with other channels

The complaint about how SMS fits the rest of the stack. “Attentive and Bluecore don't really operate cohesively,” one buyer says; another lacks “that sort of multi-channel orchestration” and is looking for a platform that can provide it. One company left Attentive because “they just couldn't support this data.” On Klaviyo SMS, a team running a search for a replacement cites email and SMS that do not sync. Most buyers work around it with manual lists and workarounds, but this is the complaint behind the clearest departure for cause here and two of the evaluations.

Named for this: Attentive · Klaviyo SMS · Postscript

Complaint 03 Often addressed internally — with the vendor's help

Flows, segments and the interface take work

The complaint about building programs. A multi-brand Attentive user finds “There isn't a way to set up a journey in one namespace and then cascade those changes across all of the namespaces,” and another wants flows “that could be modified more easily” instead of “having to go update the same piece in every single flow.” A Postscript user describes “a very messy type of UI/UX that's not very intuitive like I've seen with other companies.” Buyers lean on their account team and workarounds; none here leaves over it.

Named for this: Postscript · Attentive · Klaviyo SMS

Complaint 04 Often tolerated — and contested

Support and service level vary

Support is both a complaint and the most-praised thing in these interviews. On the complaint side, an Attentive user says “It's just that they used to be unreachable,” and another that the team “were really helpful at getting us to test new things, leverage new things. That has declined a bit.” A Postscript customer says that “once we stopped paying this exorbitant additional fee for white glove service, the service just tanked altogether,” and a Klaviyo user feels “sometimes SMS is a little overlooked from their perspective.” Most mark the vendor down and stay, and one saw service improve. On the praise side, one Attentive customer says its support is “almost like having a full-time head count.”

Named for this: Attentive · Postscript · Klaviyo SMS

Complaint 05 Often waited out — on the vendor's roadmap

Features buyers are still waiting for

The complaint about what the platform does not do yet. An Attentive user says “They were slow to adopt RCS. I still don't know when that is in their roadmap,” and another has asked to reply to messages outside the platform: “you have to go into their platform to respond to messages.” Others want transactional texts and conversational AI. Buyers mostly request and wait, and one watched an AI gap close — “So that's a weakness that has become a strength.” The exception is Klaviyo SMS, where a team without two-way messaging is shopping for a replacement.

Named for this: Attentive · Klaviyo SMS

Complaint 06 Often addressed internally — with a shorter window

Attribution that flatters the channel

The complaint about how much revenue the platform credits to SMS. One buyer “thought it was doing a lot better than it actually was until I trimmed the attribution model to about a day or two.” Another says “Attentive also over-attributes within their platform,” and a third that its API “overcounts or overattributes their revenue share.” Buyers respond by shortening attribution windows or comparing platform-reported revenue with other analytics tools; for one, it was among the reasons to switch. These changes make reporting more conservative, but attributed revenue is not the same as incremental revenue: a purchase credited to SMS may still have happened without the message. The same switcher found the alternative more conservative: “Postscript is a little bit more reserved when it comes to attribution.” Attribution windows are settings, so how generous the numbers look depends partly on how a brand configures them.

Named for this: Attentive · Klaviyo SMS

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The stories behind the complaints

A small direct-to-consumer brand liked Attentive and moved its main program to Postscript anyway. “A lot of their AI Pro tools and capabilities are expensive if you want to use them,” the buyer says, and measurement was a problem: “there's not really a good way to understand exactly what revenue is attributed to SMS without using a third-party app.” Managed service decided it: “because we're a lean team, it felt like a no-brainer to go with that option.” Lifecycle and retention director · small DTC brand
A small ecommerce brand found its SMS results looked different once it changed one setting. The buyer “thought it was doing a lot better than it actually was until I trimmed the attribution model to about a day or two,” and says “So that kind of put a sour taste in my mouth.” Now it is weighing one platform for email and SMS, with a clear condition: “We need to get the pricing down.” Marketing director · small ecommerce brand
A multi-brand retailer stays with Attentive and works around it. Journeys have to be rebuilt brand by brand — “There isn't a way to set up a journey in one namespace and then cascade those changes across all of the namespaces” — and help is slow: “I've asked for some help from my rep. I'm waiting to hear back.” The cost is momentum: “I often don't set up campaigns because I know that I need more time to set them up, which means I'm stagnant and not making progress.” CRM director · multi-brand retailer

The counter-current: what SMS buyers don't complain about

Compliance does not emerge as a complaint in these interviews; instead, some buyers praise their platforms for supporting legal requirements and screening lists. “They do a really good job on the legal compliance side and making sure we don't get sued,” one Attentive user says, and another that the platform “goes through all the customer lists constantly to make sure we are not adding people who are on the do-not-call list.” Integration is praised as often as it is faulted: “Their ability to plug in with anything we work with probably best I've seen.” Postscript's managed service draws praise of its own. And performance keeps complainers in place — one buyer says SMS is “too strong a performer to really warrant off-boarding over some site experience issues.” The pull between a dedicated SMS tool and SMS inside the email platform runs both ways here, so there is no clear consolidation trend. Before you conclude the platform is the problem, separate what the vendor controls — pricing, service, features — from what depends on your data, your attribution settings and your team's time.

What this means — whether you run one or you're buying one

If you already run an SMS platform, most complaints are lived with or worked around: buyers accept the cost of the channel, lean on their account team for flows, wait for missing features, and shorten attribution windows. The switching decisions described here involve different combinations of concerns: some buyers weigh cost alongside service or attribution, while another left Attentive because the platform could not support the customer data it needed. If you're evaluating one, our recommendations — not practices buyers describe — are to price AI and managed-service tiers alongside the base plan; to test how the platform ingests your own customer data and works with your email platform before signing; to ask what support you get without a premium tier; and to compare platform-reported SMS revenue with your own analytics using consistent attribution windows and definitions, using holdout tests where practical to see whether SMS drives purchases that would not otherwise have happened. For what triggers a move, see why brands switch SMS platforms; for cost, what SMS buyers actually pay.

Common questions

What are the most common complaints about SMS marketing platforms?

Among the Attentive and Postscript users who make up most of these interviews, six complaints recur: cost, including per-message charges and AI features sold as add-ons; getting data in and coordinating SMS with other channels; building flows and segments; uneven support; missing features such as two-way replies and RCS; and attribution that credits SMS with more revenue than buyers believe it earned. Compliance is notably absent as a complaint; some buyers praise their platforms' compliance support.

What are the biggest complaints about Attentive?

Attentive users in these interviews most often raise cost and AI tools priced as extras, difficulty bringing in custom data and coordinating SMS with other channels, uneven support, missing features such as RCS and replying to messages outside the platform, and attribution they found generous. Many of the same buyers call it the category leader, praise its support and compliance, and stay because SMS performs.

What are the biggest complaints about Postscript?

Postscript users in these interviews most often raise cost and value, an interface with a learning curve, and service that dropped after a paid support tier ended. It is also praised for its managed service and for attribution that one switcher calls more reserved.

Why do brands switch SMS platforms?

In these interviews the switches involve different combinations of concerns: cost alongside service or attribution in some, and in one case data the platform could not support. One brand moved from Attentive to Postscript on price, managed support and attribution; another moved from Klaviyo SMS to Postscript for managed service and clearer reporting; and another left Attentive over custom data it could not bring in. Several buyers with complaints say SMS performs too well to move.

Is SMS platform attribution accurate?

Some buyers in these interviews say their SMS platform's attribution credits the channel with more revenue than it earned; one found performance looked much weaker after shortening the attribution window to a day or two, and another uses a third-party app to measure it. A shorter window makes reporting more conservative but does not measure incremental revenue — purchases that would not have happened without the message. Comparing platform-reported revenue with your own analytics on consistent definitions, and using holdout tests where practical, is our recommendation, not a practice most buyers describe.

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Methodology. Alium conducts verified interviews with software buyers — the lifecycle, retention, CRM and ecommerce leaders who select and run these platforms. This page aggregates what users of SMS marketing platforms say about the platforms they run, in interviews conducted through October 2026, focusing on the complaints they raise in answer to questions about a named platform and what they did about them. Only complaints about SMS are counted; remarks about a vendor's email product are excluded, as are prospects and previous employers. Most of the evidence comes from Attentive and Postscript users. Complaints are counted by company and coded by theme; they are editorial codings of interview content, not survey scores. Ratings are averages of verified buyer ratings; the full table is on the SMS lessons page. Buyer identities are verified at interview time and anonymized before publication; vendor names are reported as given. No vendor paid to appear or was able to edit this page.