Exact Online and Mailchimp integration

What moves between them

Customer and contact data flows from Exact Online into Mailchimp. ml-connector polls Exact Online's Accounts and Contacts entities, mapping customer records to Mailchimp list members. Sales invoice data can be written to Mailchimp as e-commerce Orders to preserve order value, payment status, and date for segmentation. Reference data such as cost centers (mapped to Mailchimp tags) are synced in both directions. The main flow is one-way: Exact Online is the source of customer identity and order history, and Mailchimp is the destination for email engagement.

How ml-connector handles it

ml-connector stores both credential sets encrypted. For Exact Online, it manages the 10-minute OAuth access token lifecycle, refreshing before expiry, and uses the division ID and region-specific base URL per customer. Since Exact Online webhooks return only the entity key and action, ml-connector fetches the full entity data (customer name, email, address, invoice totals) immediately after webhook delivery, or polls at regular intervals if webhooks are not enabled. For Mailchimp, ml-connector extracts the data center prefix from the API key and constructs the correct regional endpoint. Because Mailchimp Marketing API webhooks have no signature verification, ml-connector does not validate them cryptographically. Customer records are deduplicated by email address when syncing into Mailchimp, and if a customer email exists in both systems, the more recent record wins based on timestamps. Sales invoices are mapped to e-commerce Orders, preserving the order total, currency, and payment status so Mailchimp segments can filter by invoice amount or payment date. Every record carries an audit trail and can be replayed if a downstream Mailchimp write fails.

A real-world example

A B2B software vendor runs Exact Online across operations in three European countries, managing customers, invoices, and multi-currency payments in one accounting platform. The marketing team uses Mailchimp for monthly newsletters and quarterly campaigns, but keeps customer lists in spreadsheets that go stale within weeks. With Exact Online and Mailchimp connected, new customers and address changes sync automatically from Exact Online into the main Mailchimp list. The team can segment campaigns by invoice total or payment status without re-exporting data, send targeted offers to customers in high-revenue cost centers, and suppress inactive customers. Month-end list hygiene is automatic, and the marketing team spends zero time on data entry.

What you can do

• •Sync customer accounts and contacts from Exact Online into Mailchimp lists, keeping subscriber data fresh as customers are added, updated, or removed.
• •Map Exact Online sales invoices to Mailchimp e-commerce Orders, preserving order totals, currency, and payment status for advanced segmentation.
• •Handle Exact Online's regional base URLs and rotating OAuth tokens transparently, with automatic token refresh before expiry.
• •Detect new and updated customers via Exact Online webhooks (with fallback polling if webhooks are not enabled) and write them to Mailchimp within minutes.
• •Deduplicate customer records by email address when syncing between systems, ensuring no duplicate subscribers in Mailchimp.

Questions

What customer data syncs from Exact Online to Mailchimp?

Customer name, email address, postal address, phone number, and related contact records from the Exact Online Accounts and Contacts entities flow into Mailchimp list members. If you enable the e-commerce sync, Exact Online sales invoices map to Mailchimp Orders, carrying the order total, currency, and payment status (paid, pending, refunded) so Mailchimp can segment campaigns by invoice value or payment date. You can also map Exact Online cost centers to Mailchimp tags for regional or business-unit segmentation.

Does ml-connector support Exact Online's webhook delivery or does it have to poll?

ml-connector supports both. If you enable Exact Online webhooks for Accounts, Contacts, and SalesInvoices, ml-connector listens for HTTP POST notifications and fetches the full entity data immediately. If webhooks are not enabled or you prefer polling, ml-connector queries Exact Online on a schedule you define (e.g., every 15 minutes) and compares timestamps to find new and changed records. Webhooks are faster but require a public callback URL; polling is more robust and works behind firewalls.

How does ml-connector handle the different OAuth and auth models between Exact Online and Mailchimp?

ml-connector stores encrypted credentials for both systems and manages their different token lifecycles separately. For Exact Online, it tracks the 10-minute access token and the 30-day rotating refresh token, refreshing before the access token expires. For Mailchimp, it accepts either an API key (with data center prefix extraction) or an OAuth token. Both are encrypted at rest and never logged, and ml-connector presents the correct credentials and headers on every request.