The Definitive Ecommerce Guide to List Growth

Acquisition is a fundamental part of every SMS strategy. Investing in growing your list consistently is the first step in the subscriber lifecycle. Growing your list helps positively impact all your dependent metrics and lays the groundwork for how you interact with your audience. And when you invest in it early and often, it helps you capitalize on all that hard work during high-selling periods like BFCM.

So let’s get started.

List Growth Fundamentals

Create a Desktop Popup

Popups are great for converting new website visitors into subscribers. When a nonsubscriber lands on your website, they’ll see a popup inviting them to enter their phone number to opt into your SMS list—possibly with the promise of a discount or other reward for doing so (e.g., “Sign up to get 10% off your first order.”).
Postscript enables users to create both desktop- and mobile-optimized popups directly within our platform. We also integrate with popular third-party popup builders like Amped.
One important thing to note is that popups must include compliant opt-in language, which Postscript automatically adds to your popup design.

Swipe through this gallery of DTC popup standouts before you start building your own.

Create a Mobile Popup

To provide the optimal user experience, your popup for desktop visitors should appear slightly different than your popup for mobile users. Most notably, the desktop version will require users to type in their phone numbers, whereas the mobile version should feature a simpler opt-in method.

Aside from sizing, the main difference between your desktop popup and your mobile popup is that the mobile version should allow for two-touch opt-in if you aren’t already on Postscript and benefitting from Onsite Opt-in.

Test Your Popup Offers

Consider running an A/B test to see what provides list growth faster: a discount code or a CashBack incentive, which you can now run with Fondue. Brands are used to seeing a 10% off discount code and have become accustomed to giving away those margins to acquire a subscriber. With CashBack, you can offer better incentives for the customer, give them choice (store gift card or Visa gift card) and see an average lift of 30% increase in list growth.

Learn all about Cashback here

Learn all about CashBack here

Set up Onsite Opt-in

This is the fastest way to grow your list on Postscript—whether you’re just starting out or already have an established subscriber base. Keep visitors on your site for improved SMS and email sign-up rates and more accurate attribution as well as increased conversion rates. Not only will this grow your SMS list 3x faster—it will help you grow your email list too.

Enable Collection at Checkout

A must if you want to start amassing subscribers immediately. When a customer fills out their order information, they’ll see a checkbox they can select to sign up for your brand’s text messages.

Those who check the box will be added to your subscriber list upon completion of their order. As with any other opt-in point, it’s important to display the appropriate compliance language next to the checkbox:
*I agree to receive recurring automated marketing text messages (e.g. cart reminders) at the phone number provided. Consent is not a condition to purchase. Msg & data rates may apply. Msg frequency varies. Reply HELP for help and STOP to cancel. View our Terms of Service and Privacy Policy.

Merchants using Postscript can use our software to enable subscriber collection at checkout.

Opt-in landing-page-img

Create an Opt-in Landing Page

To have a dedicated landing page, you'll need to create a specific page within your site where you can embed your opt-in form.

Once you have a dedicated page created, you'll want to create and embed a compliant opt-in form. You’ll want to make sure this page includes a clear call to action, provides a phone number field and the compliant opt-in language. It’s also important to include links to your Terms of Service and Privacy Policy.

Use this page everywhere from an Instagram story, enticing people to sign up for your VIP text list by including a link to the page. Or use it anywhere you don’t have the space to include compliant language. Drive visitors or convert customers to that list by linking them directly to your landing page instead.

Host a Giveaway

When Brock Mammoser, founder of Frost Buddy, first began building his SMS list, giveaways were key to his success. Here he explains just how he did it in our acquisition webinar.

Brock Mammoser

Brock Mammoser



“The more people we can get in there, the more profitable we are.”

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Scale Your SMS Strategy

Add Unique Opt-In Keyword to Existing Emails

Update your current email templates—and any live email automations—with a call to action asking recipients to text a particular keyword to your toll-free number (TFN) or dedicated short code (DSC) in order to opt into your SMS marketing.

Aim for something that explains what the keyword is for and any coupon included. You should also set up a custom reply for anyone that opts in using that keyword.

This is a quick, easy way to start leveraging your email audience to drive SMS subscriptions immediately (as you ramp up other email efforts). This could be as simple as adding a line like this at the bottom of every email:

“New product drops go to our text list first.

Text DIBS to 54321 to join our VIP list.”

Or, you could promise a small incentive to those who opt in:

“Love our products? Get 20% off your next order when you sign up for our text messages. Just text LOVEU to 54321.”

Be sure to display the required compliance language alongside your CTA.

*I agree to receive recurring automated marketing text messages (e.g., cart reminders) at the phone number provided. Consent is not a condition to purchase. Msg & data rates may apply. Msg frequency varies. Reply HELP for help and STOP to cancel. View our Terms of Service and Privacy Policy.


Create QR Code Shipping Insert

QR codes were made for mobile—which makes them perfect for SMS—but they’re also widely used around the world. It’s hard not to reflexively open your camera app every time you see one.

Postscript allows you to create QR codes right inside the app. You can then export the image file and use it virtually anywhere. We even build in the necessary compliance language.

When someone scans the code, their messaging app automatically launches and pre-fills a text with a message you create. The user simply needs to send the text to complete the opt-in process.

We recommend creating an insert to send with each order. Or, get creative and add the code to stickers or other promotional items.

Collect New Subscribers Using Zero-Party Data

If you’ve already used coupon codes or CashBack as incentivizing new signups, try using a popup method that collects zero-party data.

Here’s some great examples of brands doing this right.

If you’re a skincare brand and your main categories are aging, acne and inflammation, try to find out which of those buckets most affects your subscribers. Once you’ve got that information, you can segment them accordingly and make sure they are receiving messages that are most relevant to them starting at the Welcome series. This is meaningful data that can drive retention and revenue in the channel.

(Plus, here’s 13 more ways to drive conversion rates once they do opt-in!)

Update Physical Ads and Signage to
Incorporate QR Code

Brick-and-click brands have an additional play to capture subscribers in person. Add that QR code to physical marketing materials—signs, brochures, posters, mailers, business cards, trade show collateral, etc. Turn that foot traffic into site traffic!

Here’s how True Classic uses CashBack in store using QR codes.

Use Back in Stock to Gain High Intent Subscribers

Run out of your bestseller again? Use it as an opportunity to grow your list. Give shoppers an opportunity to opt into Back in Stock SMS alerts when you’re waiting for more inventory.

While other acquisition strategies often require a subscriber incentive such as a discount to entice opt-ins, Back in Stock has a built-in incentive of informing a high intent customer of when they will be able to make a purchase.

Jean Baik

Jean Baik

Co-Founder and Chief Merchandising Officer

Shop Miss A

"Postscript’s Back in Stock is a great way for people to subscribe to our list even if they ignored our popups. I love that, instead of losing that shopper because the item is out of stock, we’re able to convert them into a subscriber."

Promote SMS Opt-in on Social Channels

You’ve got a big TikTok audience? Get them on your text list. Is Instagram your biggest traffic driver? Make them wanna be on your SMS list too.

You’re still going to need to include compliance language in any call for people to sign up for your SMS list. Or simply drive them to your existing landing page right within a story or profile link.

Here’s a gallery of social media SMS plugs that we found in the wild.

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Expert Level Ideas

Product Waitlist Campaign image

Run a Product Waitlist Campaign

Hyping a new product drop or an impending restock of a popular sold-out item? Use all your normal promotion channels to invite folks to sign up for your texts so they’ll be the first to know when the product is available. Once that product is in stock, announce it via SMS before you promote it anywhere else. 

Take it a step further and promise exclusive access to the product in question for a limited amount of time (e.g., “Get first dibs when Product XYZ drops. Subscribe now to gain entry into our 24-hour SMS-only pre-sale”).

Create a segment of your best customers—based on whatever details you deem most important (spend, # orders, etc) and create a VIP customer group over text. 

If your VIPs are big spenders, don’t give them promo codes over text. Instead, just give them early access to big sales so they are the first to shop.

Host an SMS-Only Sale Event

Even if it’s not tied to a product launch or restock, an SMS-only sale event is a great tool for driving opt-ins. Let website visitors, social followers, and email subscribers know that only SMS subscribers will receive the discount code. You could even gate your website, only allowing folks to shop if they enter a special password delivered via text.

sms-only product image

Create an SMS-Only Product or Promo Series

One smart way to collect—and retain—subscribers is to create a recurring series where those on your SMS list receive something special. But go big to optimize this strategy. Go with a limited edition product, a free gift with purchase, loyalty points—anything provided at a consistent interval only to SMS subscribers.

Turn on Onsite Opt-in with CashBack

The brands taking the biggest swings with list growth are using these two features, available only at Postscript.

With Onsite Opt-in (read more about that here) you are keeping visitors on your site for improved SMS and email sign-up rates and more accurate attribution.

It works by giving visitors a one-time passcode, that they then enter leveraging autofill. They’re on your list within seconds and continue shopping.

When you include CashBack and incentivize them with a higher offer (25% CashBack versus 10% off a first order), you’re going to see up to 3x more signups.

Here’s how it worked for Jones Road.

Joanne Coffey

Joanne Coffey

Retention Marketing Manager

Jones Road

“We have gained more subscribers in the last two months using Onsite Opt-in than we have all year.”

Popup Audit Checklist

Get the Popup Audit Checklist

If you’ve already run basic A/B tests to see what incentive works best—you can go even deeper. There are small nuances to every popup (i.e. full screen vs partial screen) that have a big impact on conversions. Want the full checklist? We’ve got one from our in-house List Growth Strategist ready for you to implement.


The best integrations to take your list growth further

Use your favorite popup or form builder to collect SMS subscribers. 
Share subscribers data between Postscript and the rest of your tech stack.

See all integrations