Mailjet Migration: Move Lists Without Losing Trust

Migrate into Mailjet with a list inventory, field map, pilot import, dual-run week, and suppression validation — so campaigns keep sending and marketers trust the data.

By Lee M.Updated Aug 17, 20266 min readFact-checked

Quick answer

Migrate into Mailjet with a list inventory, field map, pilot import, dual-run week, and ESP ↔ CRM sync validation — then cut over only when the marketing team trusts the contacts. Prove one segment before you move the whole book of lists and automations.

Inventory lists and automations
Map fields and owners
Pilot one segment
Dual-run one week
Validate ESP ↔ CRM sync
Then cut over

Mailjet migration takeaways

Lists are the product — Mailjet (Sinch Mailjet) is an email platform covering marketing campaigns and transactional/API sending with a collaborative editor. Pricing is primarily send-volume based: Free list price (6,000 emails/mo, 200/day), Starter from list price, Essential from lis… A migration that moves rows but breaks suppressions or owners will burn sends/contacts and trust.
Pilot before bulk — One seller’s book or one priority segment first — fix mapping before volume.
CRM stays the system of record — Research names Shopify, WordPress, Salesforce, and Zapier on the Mailjet side — confirm the connectors your campaign loop depends on.
Watch packaging during cutover — Researched plans: Free, Starter, Essential, Premium, Custom. Never invent list prices here — confirm seats, sends/contacts, and quote terms on /pricing/mailjet/.

Mailjet migration map

Mailjet checklist

Bring these questions to every demo

Ask vendors to show the workflow live, not just describe it.

1Inventory source objectsLists, automations, automation books, suppressions, owners.
2Sign off the field mapTitles, emails, phones, owners, do-not-contact.
3Run a pilot importOne segment; fix mapping before bulk.
4Dual-run one weekMailjet is write-path; old tool is read-only.
5Validate with the marketing teamSpot-check contacts and ESP ↔ CRM sync before cutover.

1. Inventory lists and map fields before any import

Mailjet migration diagram 1. — Map meanings and owners before volume into Mailjet.

Inventory contacts, segments, campaigns, automation workflows, suppressions, and owners in the source tool.
Map each critical field to Mailjet (and to CRM where sync will write).
Decide archive-only fields — do not invent destinations for junk.
Remap departed owners to living users before volume. Worked example: a 6-person marketing team discovers 14% of open automation steps still owned by a departed AE; they remap those owners in the sheet before any Mailjet import.

2. Pilot one segment — then scale

Mailjet migration diagram 2. — Fix mapping on one Mailjet segment before you scale.

Choose one seller’s book or one priority segment (tens to low hundreds of records).
Import into Mailjet, then spot-check emails, phones, titles, and suppressions.
Run one campaign or automation session from the pilot set.
Confirm CRM received the activities before approving bulk. Worked example: a 6-person marketing team pilots Sam’s mid-market list into Mailjet, finds two title mappings wrong, fixes the map, and only then schedules the full import.

3. Dual-run one week with a hard write rule

Mailjet migration diagram 3. — One dual-run week is enough if Mailjet is truly the write path.

Declare Mailjet the write path for new lists and outreach.
Old tool becomes read-only history — no new campaigns there.
If anyone starts a new campaign in the old tool, restart the dual-run week.
End the week with seller sign-off on 20 random contacts. Worked example: a 6-person marketing team prints the rule on Slack: “New outreach only in Mailjet.” Two violations restart the clock; week two is clean and they cut over.

4. Cut over after ESP ↔ CRM sync and pod validation

Mailjet migration diagram 4. — Cut over to Mailjet only after the marketing team trusts contacts and ESP ↔ CRM sync.

Validate ESP ↔ CRM sync for creates and activities.
Freeze legacy write access.
Archive or export legacy lists you still need for audit.
Schedule the first post-cutover usage review. Worked example: a 6-person marketing team cutovers only after Priya and Sam each confirm five contacts and their last outreach appear correctly in CRM from Mailjet.

5. Inventory what must move into Mailjet

List users, historical records, templates, and integrations that must survive migration. Mark nice-to-have exports you can leave behind.

Worked example: EU/SMB teams needing marketing + transactional email in one vendor migrates active records only and archives the rest as read-only exports.

6. Run parallel cutover with a rollback path

Keep the old system read-only until Mailjet passes non-admin proof. Name a rollback owner and maximum parallel window.

Worked example: EU/SMB teams needing marketing + transactional email in one vendor caps parallel run at two weeks with daily checkpoint notes.

7. Verify counts and permissions after import

Reconcile user counts, role permissions, and a sample of migrated records. Research lists Shopify, WordPress, Salesforce, and Zapier for Mailjet. Confirm which are native vs API before go-live.

8. Inventory what must move into Mailjet