Brevo: migrate contacts without resubscribing unsubscribers

Analysis of official documentation, with no testing on a paid account.

Analysis based on official Brevo and CNIL documentation, without testing in a paid account.

The method uses two imports. Eligible contacts go into a working list. Unsubscribers and blocked addresses go into a separate file, imported with the relevant blocked status. This retains the history instead of accidentally restoring access to campaigns.

Classify the database before making changes in Brevo

Start with the type of message you intend to send. An order confirmation is part of the service the customer expects. A newsletter or commercial offer is subject to direct marketing rules. For consumers, the CNIL sets consent as the general rule, with an exception for existing customers where the offer concerns similar products or services. Each marketing message must also provide an easy way to opt out.

Add a decision column to your preparation file. Use clear values: campagne autorisée, bloqué email or à vérifier. An unknown status stays out of the mailing list until its supporting records have been reviewed.

Create two files and preserve opt-outs

Brevo documents a dedicated import process for blocklisted contacts. Prepare a file for each channel if your previous application distinguishes email, SMS and WhatsApp. This avoids turning a newsletter opt-out into a block on every type of communication.

Prepare the attributes before importing

Create the attributes you need before uploading the main file. For example: SOURCE_ACCORD, DATE_ACCORD and TYPE_MESSAGE. These are working names suggested by Logicelio. Adapt them to your internal records.

Brevo states that a custom attribute's name and type cannot be changed after creation. Choose the date format and expected values before mapping the columns. Deleting an attribute also deletes the data it contains.

Import the opt-out file with the correct channel

During the import, map the columns and choose a list dedicated to opt-outs. Before confirming, enable the option that adds contacts to the email, SMS or WhatsApp blocklist. The choice applies to every row in the file: use separate files when the channels differ. Once processing is complete, check the blocklisted column and the report.

Import active contacts into a working list

1. Keep at least one identifier per row, such as an email address or phone number.
2. Start with a small, representative sample and check the data preview.
3. Map each column to the correct attribute, then choose a list created for this migration.
4. Read the import report. Brevo identifies added, updated and rejected rows.

Brevo automatically removes duplicates from the file. The field CONTACT_ID is used to update contacts already present in the account. For an initial migration from another application, an email address or phone number remains the practical identifier.

A hypothetical example for a small French shop

A shop prepares three rows before migrating. The first comes from a newsletter form confirmed in August 2026: it joins the working list with its source and date. The second is a customer who opted out of email offers in September: it goes into the blocklisted import. The third comes from an old address book with an unknown source: it stays in the review area.

This classification gives each row a clear outcome. The team knows which contact to import, which opt-out to preserve and which record to review before running any campaign.

Check the migrated data before the first campaign

Compare the Brevo report with the totals in your two files. Open a few contact records from each group. Check the list, supporting attributes and blocklisted status for the relevant channel. Finally, retain the dated files and import reports with the migration records.

For new subscriptions, the guide to Brevo double opt-in helps you retain evidence from the form onwards. The guide to inactive contacts then helps you clean the list before a campaign. The Brevo review puts these features in the context of choosing the application.