Recently, I worked with a beauty brand to overhaul their restock communication. Their original template had a 12% conversion rate. After implementing the changes below, that number jumped to 37%.

Here's what makes the difference:

1. Clear, Action-Focused Subject Lines

The highest-performing subject lines are direct and specific:

• "Your waitlisted Hydrating Serum is back (limited stock)"
• "Now available: The Everyday Tote you wanted"

Avoid vague subjects like "Back in stock alert" or "Your wishlist update."

2. Product-Forward Content

The best notifications:

• Show the exact product with high-quality imagery
• Include key details (size, color, variant) the customer wanted
• Display pricing prominently
• Feature a single, unmissable CTA button

3. Scarcity When Real

When inventory is truly limited, indicating this drives action: "We've received 200 units, and 340 customers are on the waitlist."

This honest approach outperforms arbitrary countdown timers or vague "selling fast" language.

4. Social Proof Integration

Adding a simple review snippet or star rating reminds customers why they wanted the item in the first place.

5. Segmented Personalization

High-converting emails acknowledge the customer's relationship with your brand:

• For VIPs: "As a valued customer, you're receiving early access"
• For first-time waitlisters: "We've saved your spot for this highly-requested item"

The beauty brand I mentioned implemented these changes incrementally, which allowed us to measure the impact of each element. The biggest lifts came from product-specific imagery (8% improvement) and honest scarcity messaging (11% improvement).

What elements have you found most effective in your back-in-stock communications? The differences in performance can be dramatic with relatively simple changes.