Mailchimp to HubSpot migration.
Audiences become one database. Mailchimp bills per audience and teams respond by keeping several. Collapsing them into one HubSpot contact database is the migration, and it is where every duplicate you have been paying for twice finally surfaces.
Three audiences, one person, three opinions.
The same customer sits in the newsletter audience, the customer audience and the webinar audience with three different name spellings and two different unsubscribe states. Nobody notices while each audience sends separately. Everybody notices the week after they are merged.
Unsubscribed over here. Subscribed over there.
Mailchimp — the split audienceWhat a CSV export will not tell you.
Unsubscribe state has to win
If a person unsubscribed in one audience and not another, the merged record must honour the unsubscribe. This is a compliance decision before it is a data one, and it is the first thing we reconcile.
Tags are not a data model
Mailchimp tags carry everything the schema could not: source, interest, customer status, event attendance. They become a mix of properties, lists and lifecycle stages rather than four hundred tags carried across intact.
Merge fields differ per audience
Each audience has its own merge fields, often with the same label meaning different things. Mapping them into one property set is where the actual thinking happens.
Classic automations and customer journeys
Journeys rebuild as workflows. The branching translates; the trigger semantics and the way Mailchimp handles re-entry do not, so each journey gets walked rather than copied.
Ecommerce data if it is connected
A Mailchimp store connection carries order history that drives segmentation. That either moves to a HubSpot ecommerce integration or the segments stop working.
Sending reputation
A new sending domain with no history sends a large list for the first time and inbox providers notice. Domain authentication and a warming plan are part of the project, not an afterthought.
The sequence, start to cutover.
Discovery
Object counts, custom fields, automation and the integrations that will break on the way out, read from the source system rather than from a questionnaire.
Mapping
Field by field, including what will not carry across, agreed and signed before anyone exports anything.
Dry run
A complete rehearsal into a sandbox portal, reconciled against source counts so the gaps surface a month early rather than on cutover night.
Automation rebuild
Workflows, sequences and routing rebuilt to the new model rather than transliterated from the old one, which is how a migration inherits a decade of workarounds nobody remembers writing.
Cutover
A dated switch with the legacy system read-only for a defined window, and a rollback that was tested rather than assumed.
Post-migration support
A named engineer through the first full reporting cycle, which is when the questions actually arrive.
The first send goes to the duplicates.
Merging audiences without a deduplication rule agreed in advance produces a database where a good customer receives the same campaign twice and an unsubscribed one receives it at all. We agree the matching rule, run it in the dry run, and show you the collisions before a single email goes out.
What people ask before they commit.
Will our unsubscribes carry across?
Yes, and where a person appears in several audiences with conflicting states, the unsubscribe wins. That is both the legally safe answer and the right one.
What happens to our tags?
They get read, grouped and translated into properties, lists and lifecycle stages. Carrying tags across as tags is technically possible and almost always the wrong call, because it moves the mess rather than fixing it.
Do our email templates come across?
Not directly, and you would not want them to. Templates get rebuilt in HubSpot so they use personalisation tokens and the drag-and-drop editor properly. It is usually a couple of days of work and the result is easier to maintain.
How long does it take?
Two to five weeks for most Mailchimp accounts, which makes it one of the quicker migrations. Deduplication and consent reconciliation take the time, not the export.
Will HubSpot cost more than Mailchimp?
On licence, usually. HubSpot bills on marketing contacts, so part of the migration is deciding who is actually a marketing contact — which is a useful exercise regardless, and often removes a third of the list.
Where people go from here.
One database, one consent state.
Tell us what you are running
What the system does today, where it breaks, and when it has to work. An engineer reads it — you get an answer inside one business day, not a sequence.