Impact of email migration on marketers

“Wait, so we can just export our list from our old platform, upload it to Klaviyo, and start sending?” A potential client actually asked me that a few days ago. If I had a dollar for every time I’ve heard this, I’d have a separate revenue stream called “Migration Optimism Tax.” Let’s get real: If you think migrating to a new ESP is as simple as exporting a CSV and importing it into Klaviyo, you’re setting yourself up for a mess. Don't assume it's a 5-minute job only to get blindsided by the details. Here’s what gets missed often when brands decide, "let's just do it ourselves," and why it matters: 1. Data Cleanliness Is Non-Negotiable It’s not just about “removing bounces.” You need to hunt down and suppress dead emails from old contests, bots, fakes, and duplicates from messy imports. If you skip this, you’ll tank your sender reputation on Day 1. 2. Segmentation Logic Gets Lost in Translation Your old platform’s logic for “engaged” or “VIP” segments does not just port over. Segments are built on event data that usually doesn’t make the jump. In Klaviyo, you have to rebuild each one manually, mapping rules and sometimes starting from scratch. Test before trusting. Wrong group, wrong message, instant performance drop. 3. Preferences and History Aren’t Automatic Order data syncs from Shopify, but years of custom events, loyalty info, or tags don’t. Same for signup source or list preferences. Miss these, and you lose the context that powers your targeting and flows. Make a mapping doc before you even export. 4. Consent, Tags, and Compliance Require Attention Bulk import makes you responsible for keeping unsubscribes, bounced, and suppressed emails out of future sends. Audit opt-in status, consent dates, compliance tags—anything with legal consequences. If you get this wrong, expect complaints, spam reports, and a headache with compliance teams. 5. QA Is Where Migrations Fall Apart Every flow, segment, and campaign needs to be tested in a real inbox, not just “previewed.” Check dynamic content, make sure you don’t have broken links or “Hi, first_name.” Look at mobile and desktop. Every minute spent here saves you days of chaos later. If you think migration is easy, you’re either new to this or you’ve never checked your numbers after launch. The teams that treat migration as a technical project, not an admin task, are the ones who scale without months of cleanup. If you’ve lived through a messy migration, I want to hear your worst surprise. If you’re planning one, what’s the one thing you’re worried about?

If you’re a brand switching email or SMS providers before BFCM, here’s how to avoid a disaster. Changing platforms this close to the biggest sales period of the year is high risk. I am not going to sugar coat this or be a hype girl, it doesn't benefit me either way. Get it wrong, and you could lose deliverability, segment accuracy, or key automations when you need them most. Your BFCM transition checklist: Warm your sending domain early Gradually ramp up send volumes to protect deliverability Maintain engagement by starting with your most active subscribers. Audit and rebuild key automations Ensure welcome, abandonment, and post-purchase flows are recreated exactly as they were performing before Test triggers and timing in the new platform Migrate your segments and tags accurately Double-check that engagement windows, purchase history filters, and suppression lists are identical Preserve historical data where possible Export campaign, flow, and customer engagement data before the switch for benchmarking and audience targeting Run a side-by-side test before switching off the old provider Send small campaigns from both systems to verify deliverability and reporting match expectations Bottom line: Don’t just ‘switch and send’. Treat your ESP/SMS migration like a product launch - test, measure, and phase it in. Your Black Friday sales depend on it.

Email platform migration sometimes sounds really easy, like it is plug-and-play. The reality? You’re probably walking into a silent revenue leak. Here’s what most teams miss: 1) You lose cookie data. That means your subscriber list is technically “owned,” but your ability to recognize returning traffic drops off a cliff. 2) You have to rewarm your domain. Usually switching platforms means starting over on deliverability. What happens next? - Emails land in spam. - Retargeting performance tanks. - Attribution gets messy. We’ve seen it over and over—brands switch ESPs and don’t recover for months. Does that mean you should never switch ESPs? Not necessarily. It does mean that you have to plan for the migration the same way you’d plan a product launch. It means knowing how you will immediately restore deliverability levels (shameless plug: Revenue Roll can help here). P.S. this isn’t an attack on any particular ESP, it’s just a pattern I continue to see.