Migrating email platforms is one of the highest-risk changes an ecommerce brand makes. Done well, it unlocks better data, flows, and segmentation. Done badly, it costs revenue through lost consent, broken flows, and deliverability damage. This checklist walks through a migration to Klaviyo in the order that protects your revenue.
The short version: treat migration as a project with phases: audit, data and consent, build, warm-up, cutover, and monitoring. Do not migrate in the weeks before peak season unless you have no choice.
Should you migrate now?
| Situation | Recommendation |
|---|---|
| Peak season (BFCM) within about eight weeks | Prepare and plan now, cut over after the season unless the current platform is failing |
| Current platform cannot support needed segmentation, flows, or integrations | Migrate, with a phased plan |
| Revenue from email is strong and stable | Migrate only if the new platform adds clear value |
| Contract renewal is near | Use the date to plan, and avoid rushing |
Phase 1: Audit what you have
- ☐ List every active flow, campaign type, form, and template
- ☐ Pull performance by flow for the last 6 to 12 months so you know what to protect
- ☐ Export your segment definitions and the logic behind them
- ☐ List every integration: ecommerce platform, SMS, loyalty, reviews, subscription, helpdesk, analytics
- ☐ Identify sign-up sources: pop-ups, checkout, landing pages, social, in-store
- ☐ Note current deliverability: sending domain, complaint rate, engagement by provider
- ☐ Decide what to rebuild, what to improve, and what to retire
Phase 2: Data and consent
This phase carries the most legal and revenue risk.
- ☐ Export subscribers with consent status, timestamp, and source, not only email addresses
- ☐ Export unsubscribes, bounces, and spam complaints so they stay suppressed
- ☐ Export customer properties: order history, lifetime value, preferences, tags
- ☐ Map fields between platforms and standardize names
- ☐ Clean the list: remove invalid addresses, role accounts, and known bots
- ☐ Decide what to do with long-term unengaged contacts. Do not import them as active subscribers; sunset them or import to a separate suppressed or low-priority segment
- ☐ For SMS, export consent records with the exact language and timestamps, and confirm your new setup can honor existing opt-outs. See SMS Compliance for Ecommerce
- ☐ Have counsel review your consent trail if you are importing SMS or any list with unclear permission
Phase 3: Connect and build
- ☐ Connect your ecommerce platform and confirm that orders, products, checkout, and customer events sync correctly
- ☐ Connect integrations: loyalty, reviews, subscription, SMS, helpdesk, ads
- ☐ Set up sign-up forms and pop-ups, and confirm they tag the right sources
- ☐ Build segments, starting with engaged, new, repeat, VIP, and lapsed
- ☐ Rebuild core flows in priority order: welcome, abandoned cart, checkout abandonment, post-purchase, then the rest. See Klaviyo Flows Every Ecommerce Brand Needs
- ☐ Rebuild templates and test across clients and devices
- ☐ Set up reporting and attribution settings, and decide how you will compare performance to the old platform
- ☐ QA every flow with test profiles and real purchase paths
Phase 4: Authentication and warm-up
Deliverability is where migrations most often fail.
- ☐ Set up a sending domain and authenticate with SPF, DKIM, and DMARC
- ☐ Connect Google Postmaster Tools
- ☐ Plan a warm-up schedule that starts with your most engaged subscribers and widens gradually
- ☐ Keep sends consistent in volume during warm-up, and avoid spikes
- ☐ Monitor complaints and bounces at every step
| Warm-up stage | Audience | Notes |
|---|---|---|
| Start | Most engaged (recent clickers and buyers) | Build positive engagement signals |
| Build | Engaged in the last 60 to 90 days | Increase volume steadily |
| Expand | Broader active list | Watch provider-level results |
| Maintain | Full program with sunset policy | Return to normal cadence |
See Email Deliverability for Ecommerce.
Phase 5: Cutover
- ☐ Choose a cutover date away from major promotions
- ☐ Turn on new flows and turn off old ones in a planned sequence, to avoid gaps or double-sends
- ☐ Update forms and links so new sign-ups land in Klaviyo
- ☐ Pause old platform campaigns, but keep the account accessible for reference
- ☐ Update unsubscribe and preference links
- ☐ Check that opt-outs on either platform sync to your suppression lists during the overlap
Phase 6: Monitor and optimize
- ☐ Review flow performance daily for the first two weeks
- ☐ Compare revenue per recipient and placed order rate against the old baseline
- ☐ Watch deliverability by provider
- ☐ Fix integration gaps and data mismatches quickly
- ☐ Retire the old platform only after you are confident, and keep exports as an archive
- ☐ Document what you learned, and schedule a 30, 60, and 90 day review
Platform-specific notes
| Moving from | Watch for |
|---|---|
| Shopify Email | Limited flow logic; make sure you export subscriber consent properly and rebuild forms |
| HubSpot | Data model differences; map contact properties and lifecycle stages carefully; consider what stays in your CRM |
| Mailchimp | Audience and tag structure differences; clean your list, since contacts can sit across audiences |
| Attentive, Postscript, or another SMS platform | SMS consent and number registration; confirm sender approval before you send |
| Another ESP | Flow logic and timing differences; do not copy flows one to one without rethinking triggers |
Common migration mistakes
- Importing the full list at once and sending a big campaign
- Losing consent timestamps and sources
- Rebuilding flows exactly as they were instead of improving them
- Ignoring integrations until after launch
- Cutting over during peak season
- No baseline to compare against
- Skipping QA on real purchase paths
Timeline: what a typical migration looks like
| Week | Focus |
|---|---|
| 1 to 2 | Audit, data export, field mapping |
| 2 to 3 | Connect store and integrations, set up authentication |
| 3 to 5 | Build flows, segments, and templates; QA |
| 4 to 6 | Warm-up with engaged segments |
| 6 to 7 | Cutover |
| 8 and beyond | Monitor, optimize, expand |
Timelines vary with complexity, list size, and integrations.
FAQ
How long does a Klaviyo migration take?
Commonly several weeks for a standard store, longer with complex flows or many integrations.
Will I lose revenue during migration?
You can limit that with careful planning, a phased cutover, and warm-up. Risk is highest when consent, data, or deliverability are mishandled.
Should I migrate before BFCM?
Usually not. Plan now and cut over after the season, unless your current platform is failing.
Do I need to re-collect consent?
Not if you have documented consent and permission from your previous platform. If consent records are missing or unclear, get legal advice and consider a re-permission campaign.
Can I run two platforms in parallel?
Yes for a short overlap, with clear suppression rules so customers do not get duplicate messages.
How ATTN helps
ATTN is a Klaviyo Platinum partner agency. We run migrations end to end, from audit and data mapping to flow rebuilds, warm-up, and post-launch optimization. Talk to our retention team about a migration plan.
ATTN is a marketing agency, not a law firm. This article is general information, not legal advice. Laws and carrier rules on consent, messaging, and privacy change often and vary by state and situation, so consult your own attorney before making decisions about your program.