How to Migrate From Sailthru to Klaviyo Without Losing Flow Revenue

Direct answer: Migrating from Sailthru to Klaviyo only pays off if the migration includes building out flow automation, not just recreating existing campaigns on the new platform. Sticky Digital recommends auditing what percentage of current revenue comes from campaigns versus flows before migrating, rebuilding Sailthru's Zephyr-templated personalization using Klaviyo's dynamic content blocks and product feed, and mapping Sailthru's built-in lifecycle stages to purpose-built Klaviyo flows rather than leaving that logic undone. Brands that treat this as a like-for-like platform swap keep the same campaign-heavy imbalance they had on Sailthru, and that imbalance is usually the actual reason revenue plateaus.

Sticky Digital's Perspective

Sailthru migrations look different from most platform switches because the brands running Sailthru are usually sophisticated senders already. They've built smart lists, they've used lifecycle segmentation, their campaigns are personalized at send time. The team knows what good targeting looks like. What they haven't built, because Sailthru doesn't require it the same way, is flow architecture. Sailthru's strength is campaign-level intelligence. Klaviyo's strength is automated, always-on flow logic tied to real-time customer events, and a lot of that value goes unused if the migration just recreates what already worked on the old platform.

Email and SMS drive 30 to 50% of total store revenue for the DTC brands we manage, and within that number, flows typically account for 30 to 45% of total Klaviyo-attributed revenue despite representing under 5% of total sends. That ratio is the entire argument for why this migration is worth doing properly. A brand that migrates to Klaviyo and keeps running a campaign-first program the way Sailthru trained them to is leaving most of that flow upside on the table.

What Actually Changes When You Move From Sailthru to Klaviyo

Sailthru and Klaviyo both support personalization, both connect to ecommerce data, and both let teams build automated sends. The architecture underneath is different enough that a direct port loses most of what made each platform worth using.

Zephyr Templating vs. Klaviyo's Dynamic Blocks

Sailthru's Zephyr templating language drives a lot of the send-time personalization, pulling in product recommendations, dynamic content blocks, and conditional logic written directly into the template. Klaviyo doesn't use Zephyr. Personalization gets rebuilt using Klaviyo's native dynamic content blocks and product feed syntax, which means every Zephyr-driven template needs a rebuild, not a copy-paste. Brands that try to preserve the exact visual layout without rebuilding the logic underneath usually end up with templates that render but don't actually personalize.

Interest Keys vs. Product Catalog Behavior

Sailthru's interest key model tracks content or category affinity based on engagement, which works well for the media and content-driven roots the platform came from. Ecommerce brands using Sailthru often repurpose interest keys as a proxy for product category preference. Klaviyo doesn't need that proxy, because it reads product catalog behavior, viewed categories, and purchase history directly from Shopify. Migrating interest keys as a literal segmentation strategy misses the more precise, real-time data Klaviyo already has access to.

Built-In Lifecycle Stages Have No Klaviyo Equivalent

Sailthru's audience tools often ship with lifecycle labels already built in: new, active, at-risk, lapsed. Klaviyo doesn't pre-define those stages. They have to be built as segments or flow triggers using purchase recency, frequency, and engagement data. Brands that assume Klaviyo will just "know" who's at-risk the way Sailthru's dashboard did are missing a build step that doesn't happen automatically.

The Migration Checklist Nobody Actually Follows

Most Sailthru migration writeups focus on data export and template conversion. That's necessary, but it skips the step that actually determines whether the new program outperforms the old one.

• Pull a revenue split report first — what percentage of current email revenue comes from campaigns versus automated sends, so there's a clear target for how much flow revenue is currently missing
• Audit every Zephyr-templated campaign for the personalization logic it relies on, not just the visual layout
• Document which lifecycle stages the team currently uses and what data defines each one
• Rebuild personalization using Klaviyo's dynamic blocks and product feed, not a visual recreation of the old template
• Build actual flow architecture for each lifecycle stage identified in the audit, rather than leaving it as a campaign-only segment
• Set a gradual send cadence for the first few weeks while the team gets used to flow-first architecture instead of campaign-first habits

The revenue split report is the one step almost nobody runs before migrating, and it's the single number that tells a brand whether this migration is worth the effort. Sticky Digital pulls that number before touching a single template, because a brand running 90% of its email revenue through campaigns has a very different migration priority list than one already running a healthy flow mix.

Why Campaign-Only Migrations Leave Revenue on the Table

The specific failure we see most with Sailthru migrations isn't a broken import or a botched deliverability transition. It's a brand that successfully moves its entire campaign program to Klaviyo, keeps sending the same personalized campaigns on the same schedule, and never builds the flow architecture that would have made the migration worth doing in the first place.

This happens because Sailthru genuinely rewards campaign sophistication. Teams get good at building smart lists and personalized sends, and that skill transfers directly to Klaviyo campaigns with almost no rework. Flows are a different discipline entirely, requiring a shift from "who should get this specific send" to "what recurring behavior should trigger an always-on sequence." That shift doesn't happen automatically just because the platform changed. We've seen brands run a full year on Klaviyo still missing basic flows like browse abandonment or post-purchase, because nobody treated flow-building as a required part of the migration instead of an optional upgrade to get to eventually.

The revenue consequence is consistent: campaign-only programs commonly leave 20 to 30% of available flow revenue unbuilt, sitting as a gap the brand doesn't notice because campaigns are still performing fine on their own. Fine isn't the same as complete.

How Sticky Digital Handles a Sailthru to Klaviyo Migration

Across accounts like Murad, Divi, and Josie Maran, beauty brands with sophisticated personalization habits already built into their program, we've found the revenue split audit is what keeps the migration from becoming a lateral move instead of an upgrade.

Our process breaks into five parts:

• Revenue split audit. We pull the current campaign-to-flow revenue ratio before migration, so there's a clear baseline for what's missing.
• Personalization logic rebuild. Every Zephyr-driven template gets rebuilt using Klaviyo's dynamic blocks and product feed, not visually copied.
• Lifecycle stage mapping. Sailthru's built-in lifecycle labels get translated into explicit Klaviyo segments and flow triggers, documented so the logic doesn't live only in someone's head.
• Flow architecture build. Every core lifecycle stage gets an actual automated flow, not just a campaign segment, closing the gap the audit identified.
• 30 and 60 day performance check. Flow and campaign revenue get re-measured against the original split to confirm the imbalance actually closed.

The retention work we run for brands migrating off Sailthru always starts with that revenue split number, because it's the fastest way to tell a team what they're actually walking away from if they treat this as a simple platform swap.

FAQ

Is Klaviyo better than Sailthru for ecommerce brands?

For Shopify-native ecommerce brands, Klaviyo's direct product catalog integration and flow-based automation generally give more precise, real-time targeting than Sailthru's campaign-first architecture. Sailthru remains strong for brands with heavy content or media components, but for a store built primarily around product sales, Klaviyo's ecommerce-native data typically wins once the automation gets built out properly.

What happens to my Sailthru templates when I migrate?

They don't transfer automatically. Sailthru's Zephyr templating language is specific to that platform, so every template needs to be rebuilt using Klaviyo's dynamic content blocks and product feed syntax. The visual layout can often be closely matched, but the personalization logic underneath has to be reconstructed, not copied.

Do I need to build new flows, or can I just move my campaigns over?

You can move campaigns over with relatively little rework, but that alone doesn't capture the value of switching platforms. Flows typically account for 30 to 45% of Klaviyo-attributed revenue despite a small share of total sends, and that revenue only shows up if flows actually get built, not just campaigns.

How do Sailthru's lifecycle stages translate to Klaviyo?

They don't translate automatically. Sailthru often ships with built-in lifecycle labels like new, active, at-risk, and lapsed. Klaviyo requires those stages to be built manually as segments or flow triggers using purchase recency, frequency, and engagement data, since the platform doesn't pre-define them.

How long does a Sailthru to Klaviyo migration usually take?

The technical data migration and template rebuild typically take two to three weeks. Building out the actual flow architecture that makes the migration worthwhile often takes longer, and treating that as a separate, ongoing priority rather than a one-time setup task is what determines whether the migration pays off within the first quarter.

Brands that want the revenue split audit and flow build handled end-to-end can start at stickydigital.io/pages/contact-us. For more on how we think about flow versus campaign balance generally, the Sticky Digital blog covers the rest.

Article By: Mariel Kilroy, Co-Founder, Sticky Digital

Mariel Kilroy is the Co-Founder of Sticky Digital, a retention marketing agency specializing in email, SMS, loyalty, and subscription growth for DTC brands.