Postscript review 2026: the SMS marketing standard for Shopify

We ran Postscript for 60 days on a Shopify store with about 8,200 active SMS subscribers, sending one campaign per week plus a cart-abandonment automation. Total monthly SMS volume: ~22,000 sends. Revenue attribution from SMS: roughly $14k/month.

This is the read.

What Postscript gets right: SMS-first design

The reason a serious ecom operator chooses Postscript over Omnisend’s bundled SMS or Klaviyo’s SMS add-on is purpose-built specialization. Every detail in Postscript is designed around SMS as a primary channel, not as a feature checkbox.

Specifically:

• Opt-in widgets — Postscript ships popup, two-tap consent, scroll-triggered, exit-intent, and embedded form types, all TCPA-compliant by default. The double opt-in flow (required for legally sending US transactional + marketing SMS) is built into every widget.
• Subscriber segmentation — segment on purchase history, browse behaviour, geo, opt-in source, last-message-engagement, and subscription status (active / suppressed / unsubscribed). Klaviyo’s SMS add-on can do most of this; Omnisend’s gets you the basics.
• Reply handling — incoming SMS replies land in a unified inbox. You can assign threads to agents, auto-respond with keyword triggers, or route to a human. This is where Postscript looks more like Gorgias than like an email tool.

The first time you handle an inbound SMS conversation through Postscript vs through Omnisend’s basic reply tracking, the difference is visceral. Postscript is built for two-way SMS as a channel; Omnisend is built for outbound SMS as a campaign type.

Pricing: the math that punishes long messages

Postscript bills per segment, not per message. A “segment” is 160 characters for plain SMS, 70 characters for MMS or any message containing non-GSM characters (emoji, special punctuation). A 300-character marketing SMS = 2 segments = double the bill.

As of 2026:

For our test store at 22,000 sends/month with mostly 1-segment messages:

• Postscript Growth: $299/mo base + ~22k segments included = $299
• Klaviyo SMS add-on (equivalent volume): $300/mo base (Klaviyo email tier) + ~$200/mo SMS = $500
• Omnisend Pro bundled: $230/mo total (email + SMS, this volume fits)

Omnisend wins on bill at this volume; Postscript wins on capabilities. The right answer depends on whether SMS is a real channel for your business.

Postscript AI: subject lines and segmentation suggestions

Postscript shipped a generative AI suite in late 2024 (“Postscript AI”). Three features we tested:

1. AI Reply Generator — surfaces suggested responses to inbound SMS based on customer + order context. Saved our agents about 18 seconds per reply (median). Useful, not transformative.
2. Campaign Send-Time Optimization — predicts the best send time per subscriber based on engagement history. We A/B tested AI-recommended send time vs our existing 11am ET default for 4 weeks; AI lifted click-through 8% and revenue attribution 6%. Real, measurable.
3. AI Subscriber Insights — surfaces “this segment of subscribers responds better to X type of message”. Less actionable than it sounds; surfaces patterns we already had via manual analysis.

Net: the send-time optimization alone is worth roughly $80-150/month in lift at our store size. The bill pays for the AI suite at the Growth tier.

Postscript

SMS marketing built for Shopify operators who care about deliverability.

from $100/mo

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Deliverability and compliance

US SMS deliverability through Postscript is consistently above 97% on properly opted-in lists (measured via reply rates + carrier reject reports). International SMS varies by country — UK and Australia ship clean, parts of Europe and Latin America have more carrier-level filtering.

TCPA / CTIA compliance is the boring-but-critical part. Postscript enforces:

• Double opt-in for marketing SMS in the US (required, not optional)
• 10DLC carrier registration (handled automatically during onboarding)
• STOP / HELP keyword auto-handling per CTIA spec
• Quiet hours (default 8am-9pm local time, configurable)
• Audit log for every send, retained 7 years

Getting any of these wrong = real legal exposure. Postscript handles them by default. Klaviyo and Omnisend handle them too, but the failure modes if you misconfigure are more on you; Postscript’s defaults are stricter.

When Omnisend bundled SMS wins

Two scenarios where we wouldn’t ship Postscript:

1. SMS subscribers under ~3,000. At low volume the Starter tier ($99/mo) is too much per subscriber. Omnisend’s bundled SMS at ~$25/mo covers the same flow with cheaper per-message costs at this scale.
2. SMS is a “nice to have” for occasional broadcasts. If you’re not investing in subscriber growth, two-way conversations, and campaign cadence, Postscript’s specialization is wasted. Bundle it.

For everyone else past $50k MRR with active SMS strategy — Postscript is the standard, and our 60-day test confirms why.

60-day verdict

Keeping Postscript for the test store. The opt-in conversion alone added ~480 new SMS subscribers in 60 days; AI send-time optimization added measurable revenue lift; the unified inbox cut agent time on SMS replies enough to matter.

The split-stack cost (~$300/mo Postscript + $135/mo Klaviyo) is higher than Omnisend’s bundle ($230/mo) but the depth pays back for stores where SMS is a primary channel. We’d switch back to bundled SMS only if SMS volume dropped below 3,000 subscribers for two consecutive months.

We’ll re-test Postscript at the 12-month mark to evaluate the AI suite’s continued lift and any per-segment pricing changes. Last updated: May 2026.

Postscript

SMS marketing built for Shopify operators who care about deliverability.

from $100/mo

Try Postscript