HubSpot and Mailchimp: When Two Email Tools Is One Too Many
The integration works. The harder question is why you are running both — because HubSpot ships email, Mailchimp ships email, and the sync exists mostly to make a transition survivable.
- Connector
- Native — Mailchimp-maintained app in the HubSpot App Marketplace
- Sync direction
- HubSpot → Mailchimp for audience membership; Mailchimp → HubSpot for engagement events
- Setup time
- 20 minutes
- Availability
- Works on HubSpot Free and above; audience-level sync depends on your Mailchimp plan
| What | Direction | Detail |
|---|---|---|
| Contacts → audience members | HubSpot → Mailchimp | Driven by list membership. A contact joining a synced HubSpot list is added to the mapped Mailchimp audience. |
| Mailchimp signups → contacts | Mailchimp → HubSpot | New audience members create or update HubSpot contacts, so Mailchimp-only signup forms still populate the CRM. |
| Campaign sends | Mailchimp → HubSpot | Appear as a timeline event on the contact, with the campaign name — enough to explain why someone replied out of nowhere. |
| Opens and clicks | Mailchimp → HubSpot | Engagement events land on the timeline and can be used in HubSpot list criteria, though with less granularity than HubSpot's own email data. |
| Unsubscribes | Mailchimp → HubSpot | Flow back and mark the contact. This direction is the one that matters legally, and it is the one to test first. |
| Merge fields ↔ contact properties | Two-way, configurable | First name, last name and a limited set of custom merge fields. Mapping is manual and does not handle HubSpot's richer property types well. |
Setting it up
- Decide explicitly whether this is a bridge or a permanent setup, and write the answer down. It changes every subsequent decision.
- Install the Mailchimp app from the HubSpot App Marketplace and connect the Mailchimp account that owns the audience you actually send from.
- Map one HubSpot list to one Mailchimp audience first. Multiple audiences syncing to overlapping lists is where duplicate-send incidents come from.
- Test the unsubscribe path in both directions before sending anything real — unsubscribe in Mailchimp, confirm it lands in HubSpot, then do the reverse and see what does not happen.
- Map only the merge fields you use in templates. Mapping everything creates maintenance and delivers nothing.
- Agree one rule: which system sends what. Newsletter in one, lifecycle in the other, and never both to the same person on the same day.
Where the integration stops
- Subscription status now lives in two places. An unsubscribe in HubSpot does not automatically become an unsubscribe in Mailchimp unless you have mapped it deliberately, and that gap is a genuine compliance exposure.
- Engagement data is coarser than HubSpot's native email. You get opens and clicks; you do not get the same reporting depth, and you cannot use Mailchimp engagement in HubSpot's more advanced behavioural filters as if it were native.
- Sync is not instantaneous. Batched updates mean a list-based send in Mailchimp minutes after a HubSpot list change can miss people. Build a buffer into any time-sensitive campaign.
- Merge field mapping is shallow. Multi-select properties, dates and calculated fields do not map cleanly onto Mailchimp merge tags.
- Two sending domains, two reputations. Deliverability is managed separately in each tool, and warming a domain twice is real work you would rather do once.
The honest framing
Most searches for this integration come from one of two situations. Either you have just bought HubSpot and Mailchimp is what the marketing team has always used, or you have just bought Mailchimp and HubSpot is what sales insisted on.
Both are transitions. The integration is good at making a transition non-disruptive and bad at being a destination.
What makes it a bad destination
Consent. Every other objection is an inconvenience; this one is a risk. Two systems each holding an opinion about whether someone wants your email, with a sync that is reliable in one direction and needs work in the other, is the kind of arrangement that looks fine until somebody complains and you have to explain the architecture.
If you are going to run both for more than a quarter, invest the time in making unsubscribe symmetrical and prove it with test records. Do not assume.
What makes it a good bridge
Nobody has to stop working during a migration. Marketing keeps sending from Mailchimp while HubSpot fills with contacts, engagement history builds on the timeline, and the sales team starts seeing why a lead went warm. When you eventually move the sends across, the audience and the history are already there.
Give the bridge an end date. Bridges without end dates become architecture.