Subscription businesses have a technical challenge that standard ecommerce brands don't face: you can't treat a customer who already subscribes to a product the same as one who doesn't.

Silver Fern runs 30+ SKUs. Most customers subscribe to 1–3 products but may be interested in others. Klaviyo's native abandonment flows have no way to exclude customers at the SKU level—you can suppress all subscribers or none, but not filter by specific product. The result: a subscriber who browses the probiotic they already receive monthly gets an abandonment email for something they're already buying. Annoying at best, an unsubscribe trigger at worst.

Worse, it cuts the other way too. When a subscriber browses a product they don't yet subscribe to—a legitimate abandonment opportunity—Klaviyo can't detect that gap. Revenue gets left on the table.

Beyond the technical problem, Silver Fern's email program had other headroom. The list was healthy. Attribution was solid. But the strategy needed to evolve: tighter segmentation, a smarter product launch playbook, and lifecycle flows built for a subscription business.

Most agencies would look at the abandonment problem and say: "Klaviyo doesn't support that." We built it anyway.

Our strategy centered on three initiatives: custom-coded abandonment flows that Klaviyo can't natively support, an RFM-driven approach to every campaign and flow, and a product launch playbook that treats early adopters like VIPs

We built custom JavaScript that integrates with the Klaviyo API to detect subscription status at the SKU level. When someone abandons a browse, cart, or checkout, the code checks: are they already subscribed to this specific product? If yes, exclude them. If no, they enter the abandonment flow.

This isn't something you configure in Klaviyo's UI. It required building custom JavaScript, integrating with the Klaviyo API, and testing across 30+ SKUs. Launched in early December 2025, results were visible within 13 days.

Browse Abandonment Results:

• Conversion rate: 0.57% → 1.56% (+173.7%)
• Recipients: 95,450 → 56,554 (−40.7%)
• Revenue: $45,559 → $73,539 (+$27,980)

Added to Cart Results:

• Conversion rate: 2.41% → 4.55% (+88.8%)
• RPR: $2.89 → $4.73 (+63.7%)
• Revenue: $4,304.52 → $16,379.39 (+$12,074.52)

Abandoned Checkout Results:

• Conversion rate: 2.47% → 3.92% (+58.7%)
• RPR: $2.53 → $3.79 (+49.8%)
• Revenue: $17,026.78 → $29,658.79 (+$12,632.01)

Across all three flows combined, we would generate 2.8x more revenue just from adding in this custom code

Silver Fern uses Klaviyo's RFM (Recency, Frequency, Monetary) segmentation to drive every campaign and flow decision. Champions, Loyal, At Risk, Needs Attention, Churned—every audience decision flows from where customers sit in the lifecycle.

RFM Champions / Loyal: 1.37% conversion rate | $0.96 RPR | 0.17% unsubscribe rate

Broad Engaged List: 0.63% conversion rate | $0.45 RPR | 0.37% unsubscribe rate

Champion Advantage: 2.2x higher conversion | 2.1x higher RPR | 54% fewer unsubscribes

RFM segmentation also powered the highest-revenue campaign in the entire partnership: a subscription price change announcement on January 12 that generated $108,202 from a single send. It targeted RFM Champions, Loyal, At Risk, Cancelled, and Active Subscribers—creating urgency for lapsed customers to lock in a 20% discount before it changed. That campaign converted at 1.40% (2x the program average) and drove 1,689 orders.

The Win-Back flow—targeting At Risk and Needs Attention segments with personalized reactivation messaging—reactivated hundreds inactive customers in the first 2–3 weeks alone.

Silver Fern launches many new products per year. The sequence matters enormously.

We structured every launch in three phases: build a waitlist to create anticipation, give waitlist subscribers exclusive early access, then open to the broader engaged list. The conversion rate difference is dramatic:

Product launches drove the largest month-over-month spikes in the partnership: August up +160.3%, October up +287.9%

For a subscription-first business, email isn't just a revenue channel—it's a retention engine. We built the full lifecycle infrastructure:

• Cancellation save flow: Triggers when a subscriber cancels, offering alternatives before they're gone
• Win-back flow: RFM-based reactivation targeting At Risk and Needs Attention segments
• Subscription price change campaign: $108,202 by motivating lapsed subscribers to lock in existing pricing
• Zaymo integration: One-click subscription management from email, reducing friction for new subscribers and making reactivation seamless

Email's role in this program isn't just acquiring one-time buyers—it's keeping subscribers subscribed, reactivating those who lapsed, and ensuring the subscription business compounds over time rather than leaking.

Silver Fern Brand proves that technical sophistication creates competitive advantages most brands can't replicate.

The email program was already working. Attribution was at 50-55%. Product launches were driving spikes. RFM segmentation was in place. The opportunity wasn't fixing something broken—it was building something most agencies wouldn't know how to build.

Custom code that enables SKU-level subscription detection in abandonment flows isn't a Klaviyo feature. It's not something you can configure in the UI or request from support. It requires an AI engineer who can write custom JavaScript, integrate with the Klaviyo API, and test across 30+ products. Most agencies don't have that capacity. We did.

The result: abandonment flows that convert at 83.5% higher rates, generate $28K in additional revenue, and send to 46% fewer people—because they only reach people who aren't already subscribed to the products they abandoned.

Combined with RFM-driven lifecycle marketing, a product launch playbook that treats early adopters like VIPs (10% conversion rates vs 0.5% for broad sends), and subscription lifecycle management that keeps customers active and reactivates churned subscribers, the program generated $3.9M in 7.5 months while driving 50-55% of all store revenue.

When your email program is already working, the next level isn't "send better campaigns." It's building technical capabilities your competitors can't copy.