Switch email platforms with fewer avoidable risks

1. Prove where the list came from

Record signup source, consent wording, timestamps and any double opt-in evidence you have. Set aside purchased, scraped and uncertain contacts rather than treating every profile as sendable. For a Klaviyo to Omnisend move, Omnisend's import guide says a consent record appears only when the required timestamp and source, method or form information exist in Klaviyo. Check a minimized sample instead of assuming the green import badge proves consent.

2. Reconcile do-not-send states before any campaign

Write down counts by channel for subscribed, never-subscribed, unsubscribed and suppressed profiles before and after the move. Omnisend's Klaviyo import tool maps unsubscribed and suppressed profiles to unsubscribers; inspect the resulting statuses and opt-out dates rather than importing a separate active CSV over them. If you use a manual CSV route, establish the do-not-send state before importing sendable contacts. The tool is not a real-time sync: repeat and reconcile it near cutover if both platforms remain active. Use the gap worksheet to log counts and unresolved exceptions without customer email addresses.

3. Verify the sending domain in the new provider

Follow the new provider's setup and check the actual authentication result before a customer send. Google's sender guidelines require SPF or DKIM for all senders to personal Gmail accounts; senders above its 5,000-message daily threshold must meet additional SPF, DKIM, DMARC and one-click unsubscribe requirements for relevant marketing mail. Do not treat a DNS record copied from the old provider as proof that the new sender is authenticated. Review From-domain alignment and the unsubscribe path in a received test message.

4. Rebuild and test the essentials

Choose the flows that matter to the store, such as signup, welcome, cart recovery and post-purchase. For each, record the expected trigger, delay, exit and message. Run a controlled test identity through the path, then inspect the received message, links, personalization and unsubscribe behavior. A trigger preview helps diagnose entry conditions, but it does not prove delivery. Keep any test identity separate from real customers.

5. Warm up deliberately

Begin with recent, engaged and clearly consented subscribers, then increase volume as bounce, complaint and engagement signals allow. Omnisend's switching guidance explains that a familiar domain still uses new sending infrastructure after an ESP change and calls for gradual warm-up. Avoid changing platform, domain, list composition and campaign volume at the same moment; follow the destination provider's current plan for the actual store.

Why the warning is real

The MailerLite ledger contains 145 records. A conservative text scan found 15 excerpts involving termination, suspension, disabling, blocking or bans. Klaviyo's 155-record ledger contains 9 comparable excerpts. These counts do not predict what will happen to a prepared account, but they show why compliance work belongs before import day.

Sources checked 2026-09-28: Omnisend import and consent mapping, Google sender requirements, and Omnisend ESP-switch guidance. The review-keyword counts above come from selected operator-supplied MailerLite and Klaviyo ledgers checked 2026-07-22; they are not suspension rates for either provider.