Agency Migration Guide
Mailchimp to HubSpot Migration
What actually transfers, what quietly does not, and what has to be rebuilt by hand.
We mapped Mailchimp against HubSpot feature by feature: 64 features, 5 synced objects, 8 documented traps and 28 items that have to be rebuilt. The whole map is on this page, ungated.
The PDF is the same reference, formatted to send to a client.
Get The Guide And The Calculator
The full Mailchimp to HubSpot reference as a branded PDF you can send straight to a client, plus the Excel calculator we scope these migrations with: every one of the 64 features as a row, enter your counts, get hours.
Three files: the guide as a PDF, the same guide unbranded in Markdown for your AI tool, and the full Excel effort calculator.
Mailchimp to HubSpot is a low to moderate migration, typically 2-4 weeks. Of 64 features we mapped, 44 carry across as they are and 18 land with something lost. The work is not moving records: it is the 28 items nothing moves for you.
Migration Scorecard
- Migration complexity
- Low to moderate
- Typical timeline
- 2-4 weeks
- Recommended method
- HubSpot Smart Transfer for initial contact data migration, supplemented by CSV export/import for historical data, segments, and suppression lists. Manual rebuild for all marketing assets, automations, and templates.
- Native sync
- Data sync, two way
- Smart transfer
- Supported
- HubSpot subscription
- Free for email-only sync. Data Hub Starter ($45/mo) required for custom field mappings and two-way sync of additional fields beyond email address.
Feature parity across 64 capabilities
- Maps directly: 44 (69%)
- Maps partially: 18 (28%)
- No equivalent: 2 (3%)
5
Objects synced natively
8
Limitations and traps
28
Manual rebuild items
4
Source editions covered
Where this comes from: Our own research corpus, verified 2026-07-31, behind every number on this page.
The Five Objects That Sync Natively
What the connector moves for you, and which way each one flows.
Subscribers/Contacts
Two wayBecomes Contacts
On Data Hub free tier, only email address syncs as the default field. First Name and Last Name are considered custom fields in Mailchimp and require Data Hub Starter for mapping. Custom field mappings available with paid tier.
Audiences/Lists
Into HubSpotBecomes Lists (Static or Active)
Mailchimp audiences can be mapped to HubSpot lists. Smart Transfer supports one-time list import. Multiple audiences can map to different HubSpot lists.
Tags
Into HubSpotBecomes Contact Properties (text field)
Tags can only be mapped ONE-WAY from Mailchimp to HubSpot text fields. The sync engine cannot create tags in Mailchimp because they function differently than standard contact properties. No bidirectional tag sync is possible.
Email Activity (campaigns)
Into HubSpotBecomes Contact Timeline Activity
Email activity syncs every 15 minutes for existing HubSpot contacts. Only campaigns sent within the last 30 days before connecting are included. Campaigns must have non-empty subject lines and titles, must NOT be part of an A/B test, and must NOT be part of a Customer Journey. Activity toggle must be enabled in integration settings.
Email templates
Into HubSpotBecomes Email templates
Email templates transfer, so they do not all need manual rebuilding. Documented in HubSpot's Smart Transfer data sync object mappings (knowledge.hubspot.com/integrations/supported-apps-for-hubspot-smart-transfer, read 2026-07-31).
Eight Things the Sync Does Not Tell You
Each one is documented, and each one has ended a migration in a bad week.
Free Tier Syncs Email Only
On Data Hub free plan, only the email address field syncs between HubSpot and Mailchimp. All other fields including First Name and Last Name are considered custom fields in Mailchimp and require Data Hub Starter or higher.
Workaround: Upgrade to Data Hub Starter ($45/mo) to enable custom field mappings.
Tags Cannot Sync Bidirectionally
The sync engine cannot create tags in Mailchimp because tags function differently than normal contact properties. Tags can only be mapped one-way from Mailchimp to HubSpot text fields.
Workaround: Map Mailchimp tags to HubSpot single-line text or multi-line text properties. Use HubSpot contact properties and list membership to replicate tag-based segmentation.
Groups Not Supported
Mailchimp Groups (used for newsletter categories and interest-based segmentation) do not sync through the native integration.
Workaround: Recreate Groups functionality using HubSpot custom contact properties (checkbox or dropdown) and active lists for segmentation.
30-day Email Activity Lookback Limit
HubSpot will only sync email campaign activity from Mailchimp for campaigns sent within the last 30 days before the integration was connected. Historical campaign data beyond 30 days is not retroactively imported.
Workaround: Export historical campaign reports from Mailchimp as CSV before disconnecting. Store as reference data or import key engagement metrics as custom contact properties.
A/B Test and Customer Journey Campaigns Excluded
Email campaigns that are part of an A/B test or a Mailchimp Customer Journey do not sync activity data to HubSpot contact timelines.
Workaround: Export A/B test and Customer Journey performance data separately from Mailchimp reporting before migration.
Required Merge Tags Block Sync
HubSpot cannot sync contacts to a Mailchimp list that has required merge tags because HubSpot does not send values for those tags.
Workaround: Remove required merge tag settings from Mailchimp audience fields before enabling the sync, or make the fields optional.
No Retroactive Contact Sync for non-HubSpot Forms
HubSpot will not retroactively add contacts to a Mailchimp list who submitted a non-HubSpot form before the Mailchimp account was connected.
Workaround: Manually export and re-import pre-existing form submission contacts, or trigger a re-sync by updating a property on those contacts.
Legacy Integration Is One-way Only
The older (non-Data Sync) Mailchimp integration only syncs contacts FROM HubSpot TO Mailchimp, not vice versa. Many users still have this version installed.
Workaround: Upgrade to the HubSpot Data Sync version of the Mailchimp integration for bidirectional sync capabilities.
Two Mailchimp Features HubSpot Cannot Replace
Not a workaround away. If a client depends on one of these, it belongs in the conversation before the contract.
Predicted Demographics
HubSpot does not provide AI-predicted demographics. Third-party enrichment tools (Clearbit, ZoomInfo) can supplement.
Postcards (Direct Mail)
HubSpot has no native direct mail. Use third-party integrations like Lob, PostPilot, or Sendoso.
The 28 Items That Get Rebuilt by Hand
This is the list that separates a quote that holds from one that does not.
Data And Objects
Contact Segments and Smart Segments
Mailchimp segments are saved filter definitions over audience fields and engagement.
Subscription Preferences and Subscription Types
Mailchimp models subscription at the audience level; HubSpot models it per subscription type on one contact record.
Suppression and Unsubscribe Lists
Unsubscribed and cleaned addresses across audiences.
Groups and Interest Categories
Mailchimp groups are subscriber-selected interest flags.
Historical Campaign Performance Older Than 30 Days
Mailchimp retains campaign reporting that does not move with the contacts.
Contact Star Ratings and Engagement Scoring
Mailchimp assigns a 1-to-5 engagement rating per contact.
Automation
Customer Journeys
Mailchimp's visual journey builder with branching and delays.
Automation Sequences and Drip Campaigns
Classic Mailchimp automations preceding Customer Journeys.
RSS-to-email Campaigns
Campaigns generated from a feed on a schedule.
Transactional Email Templates
Mandrill-backed transactional sends.
A/B Test Configurations
Subject line and content split tests.
Send-time Optimization Settings
Mailchimp's per-recipient send timing.
Reporting
Campaign Performance Reports and Analytics
Per-campaign opens, clicks and conversions.
Audience Growth Reports
Subscriber growth and churn over time.
Comparative Reports and Benchmarks
Mailchimp compares performance against industry peers.
E-commerce Purchase Tracking Reports
Revenue reporting from a connected store.
Sales And Marketing Config
Email Templates With Custom HTML and CSS
Mailchimp templates, both builder-made and coded.
Landing Pages
Mailchimp landing pages with their own hosted URLs.
Sign-up Forms and Embedded Forms
Forms embedded across the site posting to Mailchimp.
Pop-up Forms
Mailchimp pop-up capture.
Domain Authentication
SPF, DKIM and DMARC records pointing at Mailchimp.
Social Media Post Scheduling
Scheduled posts from Mailchimp.
Users And Permissions
User Accounts and Roles
Mailchimp users with account-level roles.
API Keys and Integrations
Keys held by external systems writing into Mailchimp.
Integrations
E-commerce Integrations
Shopify, WooCommerce and similar connected to Mailchimp.
Website Form Integrations
Third-party form tools posting into Mailchimp.
CRM Integrations Connected Through Mailchimp
A CRM syncing to Mailchimp rather than directly.
Zapier Automations Referencing Mailchimp
Zaps triggered by or writing to Mailchimp.
The Sequence
Sync First, Then Migrate
Order is the content here. These are a dependency chain, and running them out of order is a documented way these migrations fail.
- 1
Audit Mailchimp
Inventory all audiences, segments, tags, groups, automations, Customer Journeys, templates, forms, landing pages, and integrations
- 2
Export All Data
Download subscriber lists (all statuses including unsubscribed/cleaned), campaign reports, automation reports, and audience analytics as CSV
- 3
Configure HubSpot
Set up email sending domain with SPF/DKIM/DMARC authentication, create subscription types, configure compliance settings
- 4
Create HubSpot Properties
Map Mailchimp merge fields and tags to HubSpot contact properties with matching data types
- 5
Import Contacts
Use Smart Transfer or CSV import with careful field mapping. Import unsubscribed and bounced contacts separately with appropriate opt-out status
- 6
Recreate Segments
Build HubSpot active lists to match Mailchimp segment criteria
- 7
Rebuild Email Templates
Export HTML from Mailchimp templates, adapt for HubSpot email editor or create from scratch using HubSpot drag-and-drop builder
- 8
Rebuild Automations
Document all Customer Journeys and automation workflows, recreate as HubSpot workflows with equivalent logic
- 9
Recreate Forms
Build HubSpot forms and update all embed codes on external websites
- 10
Warm up Sending Domain
Start with small, highly-engaged segments (1-2% of list). Gradually increase volume over 4-6 weeks
- 11
Test Thoroughly
Send test campaigns, verify tracking, validate form submissions, check workflow triggers
- 12
Cutover
Disable Mailchimp sending, activate all HubSpot workflows, monitor deliverability closely for 30-60 days
Typically 2-4 weeks end to end, depending on how much of the source configuration is actually in use.
Effort Estimator
How Big Is This Migration?
A handful of questions, no email required. The ranges come from the research above: every feature we mapped carries an effort figure, and this adds up the ones that apply to you.
Estimated Effort
Answer a couple of questions and an hours range appears here.
Built from our research on 64 Mailchimp features. It is a range, not a quote.
A planning range, not a quote. It is delivery effort only, with no project management line and no agency markup, so add your own. What moves it most in practice is data quality.
What Goes Wrong Most Often
The failures that show up again and again, in roughly the order they bite.
Failing to Import Unsubscribed and Bounced Contacts Causes GDPR/CAN-SPAM Violations When Those Contacts Are Re-emailed From HubSpot
Failing to import unsubscribed and bounced contacts causes GDPR/CAN-SPAM violations when those contacts are re-emailed from HubSpot
Sending to Full List Immediately Without Domain Warm-up Damages Sender Reputation and Causes Deliverability Problems
Sending to full list immediately without domain warm-up damages sender reputation and causes deliverability problems
Mailchimp Groups Do Not Have a Direct Equivalent; Requires Custom Property and List-based Workaround
Mailchimp Groups do not have a direct equivalent; requires custom property and list-based workaround
Campaign Activity Older Than 30 Days Is Lost If Not Exported Before Migration
Campaign activity older than 30 days is lost if not exported before migration
Embedded Mailchimp Form Codes Across Website Properties Must All Be Updated to HubSpot Forms
Embedded Mailchimp form codes across website properties must all be updated to HubSpot forms
Mailchimp Merge Tags in Email Templates Must Be Converted to HubSpot Personalization Tokens
Mailchimp merge tags in email templates must be converted to HubSpot personalization tokens
Free Data Hub Tier Only Syncs Email Address; First/last Name Require Paid Tier
Free Data Hub tier only syncs email address; first/last name require paid tier
Double Opt-in Settings in Mailchimp Should Be Replicated in HubSpot to Maintain GDPR Compliance
Double opt-in settings in Mailchimp should be replicated in HubSpot to maintain GDPR compliance
If Using a New Sending Domain/subdomain, ISPs Treat It as Unknown and Require Gradual Warm-up Over 4-8 Weeks
If using a new sending domain/subdomain, ISPs treat it as unknown and require gradual warm-up over 4-8 weeks
Questions
Mailchimp To HubSpot, Answered
Yes. Data sync, two way, covering 5 objects. Smart transfer is supported. What it does not do is rebuild configuration: that is the 28 items below.
Typically 2-4 weeks. Complexity is driven by automation and reporting depth, not by record count: the connector moves records, so a large database is not by itself a long project.
Of 64 features we mapped, 44 (69%) carry across directly and 18 (28%) map partially, meaning something is lost or reshaped. 2 have no HubSpot equivalent at any tier.
28 items have to be rebuilt by hand, and 8 documented limitations are not surfaced by the connector at all. The full list of both is on this page.
Free for email-only sync. Data Hub Starter ($45/mo) required for custom field mappings and two-way sync of additional fields beyond email address.
2: Predicted Demographics, Postcards (Direct Mail). If a client depends on one, it belongs in the conversation before the contract.
Only in one direction. The sync is not bidirectional here, so a parallel period means picking a system of record and accepting drift in the other.
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