Once Klaviyo is connected (see the Setup Guide above), the real value comes from choosing the right segments to mail — and setting up the automation so it sends the right volume, to the right people, without surprises on your bill. This guide covers use cases and best practices for getting the most out of Klaviyo-triggered direct mail.
Why pair direct mail with Klaviyo
Klaviyo already knows who's engaging with your email and SMS — and, just as usefully, who isn't. Direct mail is a strong complement precisely because it doesn't depend on an inbox or a phone: a handwritten card lands in front of someone even if they've stopped opening your emails entirely. Pairing the two lets you build a genuinely omni-channel flow: Klaviyo owns the fast, cheap touches, and LettrLabs owns the tangible, high-attention one for the moments that matter most.
Good segments to start with
Re-engagement / winback: subscribers who haven't opened an email or clicked an SMS in 30+ days. This is one of the most common Klaviyo segments used with LettrLabs, since it targets people email and SMS have already stopped reaching.
First-time buyers: welcome new customers with a thank-you card shortly after their first order, reinforcing the relationship beyond an automated email receipt.
VIP / high-value customers: a segment of your top spenders is a natural fit for a higher-touch, premium card design.
Abandoned cart or browse abandonment: for a subset of high-intent abandoners who don't convert from email/SMS alone, a follow-up card can be a strong final nudge.
Narrowing your segment with filters
You don't have to mail everyone in a segment. Use profile filters (AND/OR) inside the automation to further target who actually receives a card — for example, restricting a winback segment to customers above a certain lifetime value, or a specific geography, so your mail budget goes toward the recipients most likely to respond.
Controlling volume and spend
Set a Monthly Sending Limit on every Klaviyo automation. As a segment grows, this cap is what keeps your postage spend predictable and prevents an automation from mailing thousands of cards unexpectedly the day a large batch of profiles crosses into a segment.
Proving it's working with Holdout Testing
If you want to know whether the direct mail itself is driving incremental results — not just correlating with customers who were already going to convert — enable Holdout Testing on the automation. Setting a holdout percentage (25–50%) automatically withholds that share of otherwise-qualifying profiles from being mailed, so you can compare outcomes between the mailed group and the holdout group.
Use Testing status before scaling up
Before activating a new segment-based automation, leave it in Testing status for a few days and add a handful of profiles to the segment yourself. Nobody is mailed while an automation is in Testing status, so it's a safe way to confirm your segment and filters are catching exactly who you expect before it goes live and starts spending on postage.
Set expectations around timing
LettrLabs checks Klaviyo segment membership on a recurring daily schedule rather than instantly, so there's typically up to a day of lag between a profile joining your segment and a card being queued. Build that into any time-sensitive segment (for example, a "just missed a restock" segment) rather than expecting same-hour delivery into the mail queue.
Keeping it running smoothly
If your Klaviyo connection is ever revoked or expires, any automations tied to it are automatically deactivated — reconnect Klaviyo and reactivate the automation to resume sending.
Automations can be switched to Inactive at any time if you need to pause a campaign (e.g., during a promotion) without losing your configuration.
Want help designing your first campaign? Reach out to our team — we're happy to help mock up card designs using your brand assets.