Postscript SMS Flows: Every Shopify Brand's Essential Automations

Postscript is the leading SMS marketing platform for Shopify brands, and its strength lies in two things: the depth of its Shopify-native data integration and the quality of its automation flow builder. When set up correctly, Postscript flows run on autopilot — delivering the right SMS message at the right moment in the customer journey without requiring ongoing manual intervention.

This guide covers the six SMS flows with the highest ROI for Shopify brands, how to build each one in Postscript, compliance considerations built into the platform, message copy best practices, timing and frequency guidelines, and how Postscript flows complement your email marketing strategy.

Why Postscript Is the Right SMS Tool for Shopify Brands

Postscript was built specifically for Shopify. Its integration is native — not a generic API connection, but a deep data sync that gives Postscript access to your Shopify order data, product catalogue, customer tags, and purchase history in real time. This data powers everything from flow triggers to personalised message content to audience segmentation.

The Postscript flow builder lets you build multi-step SMS sequences triggered by Shopify events, with conditional branching based on subscriber behaviour and customer data. Unlike basic SMS platforms that only support simple one-message automations, Postscript supports multi-step sequences, A/B testing within flows, time-delay conditions, and subscriber response routing.

Compliance Built Into Postscript

Before covering the flows, it is worth understanding how Postscript handles compliance — because SMS marketing requires more care than email.

Postscript manages TCPA compliance by design. All opt-in forms, checkout opt-in prompts, and keyword campaigns include the required consent language automatically. The platform enforces double opt-in for new subscribers by default: subscribers receive a confirmation text after signing up and must reply YES before they can receive marketing messages.

Postscript also handles opt-outs at the infrastructure level. Any subscriber who replies STOP, CANCEL, UNSUBSCRIBE, or similar keywords is automatically removed from your SMS list and cannot receive further messages — including automated flows. You cannot override this, and you should not want to.

Quiet hours can be configured globally in your Postscript settings, ensuring no messages are sent outside of acceptable time windows (typically 9am–8pm in the subscriber’s local timezone, where timezone detection is available).

For UK and EU brands, ensure you have documented explicit consent before sending any SMS marketing messages. Postscript’s opt-in forms include the required consent language, but you are responsible for ensuring your data collection practices meet local regulatory requirements.

Flow 1: Welcome Series

The welcome flow is triggered when a new subscriber opts into your Postscript list. It is the highest-ROI flow in most SMS programmes — subscribers are at peak attention immediately after opt-in.

Message 1 (immediate): Deliver the welcome offer. Keep it under 160 characters if possible. Format: “[Brand]: Welcome! Here’s your [X%] off: [CODE]. Shop now: [link]” Plus the required “Reply STOP to opt out.”

Message 2 (day 2, if no purchase): A softer re-engagement without urgency pressure. Introduce a product category or brand benefit. Link to a specific bestseller or category page.

Message 3 (day 5, if no purchase): Urgency on the offer expiry. “Your [X%] discount expires tomorrow — don’t miss out: [link]”

Set purchase-triggered exits at every step. A subscriber who buys after Message 1 should not receive Messages 2 and 3 — the welcome sequence has served its purpose.

Postscript’s welcome flow template library includes a tested starter version of this sequence. Use it as a starting point, then customise the copy and offers for your specific brand.

Flow 2: Abandoned Cart Recovery

The abandoned cart flow is typically the highest-revenue-generating flow for brands with established SMS lists. Postscript triggers this flow from Shopify’s cart abandonment event.

Message 1 (1 hour): Direct, no-frills reminder. “[Brand]: You left something behind. Your cart is saved: [link]” If your average cart value is high enough, optionally add “Free shipping still applies.”

Message 2 (24 hours, if no purchase): A follow-up with a small incentive or urgency element. “Still thinking? Your cart expires soon — and we’ll cover shipping if you complete your order today: [link]”

Keep cart recovery SMS copy shorter than cart recovery emails. SMS is interruptive by nature — subscribers see the notification immediately. They do not need a lengthy message; they need a clear link and a reason to act.

For high-value carts (above 2x your AOV), consider a two-message flow rather than three. High-intent purchasers with large carts often abandon due to decision hesitation rather than price sensitivity — a second aggressive incentive message can feel pushy rather than helpful.

Flow 3: Post-Purchase Thank-You and Order Confirmation

A post-purchase SMS is one of the most underused flows in Postscript. Most brands rely entirely on email for post-purchase communication, but an SMS at the right moment adds a premium feel to the customer experience.

Message 1 (immediate, on order confirmation): A brief, warm thank-you. “[Brand]: Thank you for your order! Your [product] is on its way. Track it here: [link]” For brands selling high-value or considered products, this message makes the customer feel valued at the moment they are most invested.

Message 2 (optional, day 7 after delivery): A product check-in. “How’s your [product] treating you? We’d love to hear from you — leave a quick review: [link]” This drives reviews without relying solely on email.

Keep post-purchase SMS messages to a maximum of 2 messages per order to avoid overwhelming customers who have already converted.

Flow 4: Checkout Abandonment

Checkout abandonment is higher-intent than cart abandonment — this subscriber reached the payment screen before dropping off. Postscript supports a separate checkout abandonment trigger, distinct from the cart abandonment event.

Because checkout abandonment indicates stronger purchase intent, this flow warrants more direct messaging and a faster initial response.

Message 1 (30 minutes after checkout abandonment): “[Brand]: You were so close! Complete your order here: [link] — your cart is still saved.”

Message 2 (3 hours, if no purchase): Add a small incentive. “Still there? We’ll cover your shipping if you complete your order today: [link]”

In Postscript, you can layer the checkout abandonment flow on top of your cart abandonment flow, but add a segment filter to ensure contacts do not receive both simultaneously for the same session. A subscriber who abandons checkout and is already in the cart abandonment flow should be exited from the cart flow and entered into the checkout flow.

Flow 5: Back-in-Stock Alerts

Back-in-stock SMS flows are among the highest-converting flows you can run in Postscript. Subscribers who signed up to be notified about a specific out-of-stock product have demonstrated explicit intent — they want this specific item.

Setup requires either a Postscript integration with a back-in-stock app (Back In Stock by Swym, Notify Me, or similar) or a custom webhook that fires the Postscript trigger when a product variant becomes available.

Message 1 (immediate, on restock): “[Product] is back! Get yours before it sells out again: [link]” Add a real-time inventory signal if available: “Only 50 units available.”

This flow needs to be fast — back-in-stock items sell out quickly, and a subscriber who gets the notification 4 hours after a restock often finds the item unavailable again. Configure the trigger to fire as close to real-time as your integration allows.

Flow 6: Win-Back Flow

The win-back flow targets lapsed buyers who have gone quiet. In Postscript, this flow is triggered by a segment entry event — when a customer moves into your “lapsed” segment, defined by their last order date.

Message 1 (on segment entry, after 120+ days since last purchase): “[Brand]: We miss you. Here’s 15% off your next order — just for you: [CODE] [link]”

Message 2 (day 7, if no response or purchase): A second attempt with a softer angle. Introduce a new product or collection they may not have seen. “Something new you might love: [product] [link]”

Keep win-back SMS flows to 2 messages maximum. Unlike win-back email sequences that can run 3–5 messages, SMS win-back at higher frequency feels intrusive for subscribers who have already gone quiet.

SMS Copy Best Practices

SMS copy has unique constraints. Every word is expensive — literally, since longer messages trigger multi-part billing — and subscriber attention is limited to a notification preview before they decide to open.

Brand the message at the start. Many SMS notifications strip sender information in the notification bar, so starting with “[Brand]:” ensures the subscriber knows who is contacting them.

One CTA per message. SMS cannot support multiple competing calls to action. Every message should have one link and one clear instruction.

Keep the link prominent. Put your Postscript-shortened link near the end of the message, after the copy justifies the click.

Include opt-out language. “Reply STOP to opt out” is required by TCPA. Postscript adds this automatically, but be aware of how it affects your character count.

Use emoji sparingly. One or two emoji in an SMS message can increase open rates modestly, but emoji-heavy messages feel like spam. Reserve them for high-energy moments like product launches or sale announcements.

Combining Postscript SMS With Email Marketing

SMS and email serve different roles in a multi-channel strategy. Email allows depth — longer content, richer design, more nuanced storytelling. SMS provides reach and immediacy — it is seen faster and responded to faster than email for most subscribers.

The most effective approach is to use SMS as a complement to email rather than a replacement. For your abandoned cart flow: email fires first (1 hour), SMS follows (3 hours) for subscribers who are SMS-opted-in and have not yet purchased. For flash sale campaigns: email goes out in the morning, SMS goes out mid-afternoon for subscribers who are SMS opted-in — catching those who missed the morning email.

With Postscript specifically, the connection to email flows requires either a shared customer platform (like Klaviyo, if you use both tools) or manual coordination. If you use Klaviyo and Postscript together, Klaviyo Flows and Postscript Flows can share a Shopify customer identifier, and you can use Postscript segments and Klaviyo lists together to coordinate who receives which channel at which time.

Getting Your Postscript Flows Right

The brands generating the most revenue from Postscript SMS flows are not necessarily sending the most messages — they are sending the right messages to the right subscribers at the right moment. That requires clean automation logic, strong copy discipline, and a strategy that treats SMS as a premium channel with its own set of rules.

At Excelohunt, we build Postscript SMS flow strategies for Shopify brands from end to end — compliance setup, flow architecture, copy, and integration with your email platform. If you want your SMS flows to drive real revenue, our team can build them correctly.

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