Can I migrate in stages?

Yes. A staged migration is preferred because each stream can be verified before the next one moves.

Do the migration connectors send email through my old provider?

No. Migration connectors are read-only sources used to inventory and map your existing setup. Sending happens from Send & Retain after the destination is configured and verified.

Will every automation import one-for-one?

No. Provider concepts differ, and some sources expose less automation detail than others. For example, the Mailchimp connector reads legacy automations rather than every modern journey. The migration plan records what can be mapped, what must be rebuilt, and what should be retired.

Migrate

Move your email system without a blind cutover. Keep consent, customer state, and delivery evidence.

Inventory the source, rebuild only the useful lifecycle, and switch one verified sending stream at a time.

Build my migration plan Read the docs

✓Move one controlled stream first.

Migration control

Migrate

Inventory before cutover

Inventory

Source material read

Rebuild

Created paused

Verify

Real inbox test

Switch

One trigger first

Destination flow

Paused until validation and explicit cutover

paused

The source stays availableInspect

[ 01 / 03 ]Why migrations fail

An export is not an email system.

Contacts are only one layer. The risky parts are consent, suppressions, event semantics, template variables, flow exits, domain reputation, and the messages still in flight.

Identity drifts

Lists, profiles, tags, and custom fields rarely describe the same person in the same way.

Triggers change meaning

A copied automation is unsafe if its entry event or exit condition behaves differently.

Consent gets flattened

Unsubscribes, bounces, complaints, and topic preferences must survive the move intact.

Evidence disappears

Without a baseline, a post-cutover dip is difficult to detect and harder to explain.

[ 02 / 03 ]Choose your source

Start with the provider you are leaving.

Klaviyo

Preserve profiles and consent, then rebuild useful flows around current product events.

Mailchimp

Reconcile audiences and suppressions while documenting Customer Journeys the API cannot expose.

ActiveCampaign

Keep meaningful fields and tags, then simplify live automations into explicit event paths.

Resend

Keep the developer workflow while adding contacts, events, flows, and message evidence.

Mailgun

Preserve API call contracts, templates, suppressions, and callbacks while adding lifecycle context.

SendGrid

Untangle authentication, templates, contacts, events, and journeys before routing traffic.

Postmark

Move critical message streams one at a time without weakening transactional safeguards.

Customer.io

Isolate email journeys from multichannel dependencies and preserve product-event meaning.

[ 03 / 03 ]Controlled cutover

Read the source. Rebuild the destination. Switch only what you can verify.

The Klaviyo, Mailchimp, ActiveCampaign, Brevo, and HubSpot connectors are read-only migration sources. Send & Retain inventories what exists; it does not write back to the provider you are leaving. Other providers follow a documented export-and-map path.

Reconcile contacts against suppressions before importing either.
Rebuild flows from product events instead of copying provider labels blindly.
Move one sending stream first, retain identifiers, and compare delivery evidence.
Keep rollback criteria explicit until the new stream is stable.