Mailchimp to Brevo Migration: A Step-by-Step Guide to Avoid Reputation Loss

Switching ESPs is often necessary as your business grows. However, a poorly executed migration from Mailchimp to Brevo can instantly destroy the sender reputation you spent years building.

When you change ESPs, you are essentially changing your sending infrastructure. ISPs suddenly see your trusted domain sending from a new, unrecognized IP address. If not handled systematically, your emails will be blocked.

The 5-Step Migration Framework

Step 1: Audit and Export Data

Before touching Brevo, clean your existing list. Export your engaged subscribers from Mailchimp. Do not export unengaged or bounced contacts — start fresh.

Step 2: Import and Authenticate

Import your cleaned CSV into Brevo. Authenticate your domain by updating DNS records with Brevo's SPF and DKIM keys. Do not delete old Mailchimp records until migration is complete.

Step 3: Recreate Templates & Automations

Mailchimp and Brevo use different merge tag syntax (*|FNAME|* vs {{ params.FNAME }}). Recreate core templates and test thoroughly.

Step 4: IP Warmup

If assigned a dedicated IP on Brevo, warm it up over 2-4 weeks by sending to your most engaged segment first.

Step 5: Cutover and Monitoring

Switch your domain's traffic to Brevo. Monitor Google Postmaster Tools for the first 72 hours to ensure spam complaint rates stay under 0.3%.