Migrate from ChartMogul to Mailchimp

ChartMogul's parent Customer record holds email, name, company, tags, custom attributes, and notes. We map these to Mailchimp Contact fields: email_address, first_name, last_name, company. External IDs from ChartMogul (customer UUID and external_id) are stored in Mailchimp merge fields (CM_UUID, CM_EXTERNAL_ID) for reconciliation. For customers with multiple billing sources, we consolidate to a single Mailchimp contact and note the multi-source relationship in a merge field. Duplicate detection uses email as the dedupe key per Mailchimp audience rules.

Each billing source (Stripe, Chargebee, Recurly) creates a child Data Source Customer in ChartMogul with its own invoice history. During migration, we extract the data_source_name (e.g., 'Stripe', 'Chargebee') and store it as a Mailchimp tag (ds_stripe, ds_chargebee). The primary billing source is also stored as a merge field ds_primary. This preserves the multi-source relationship without duplicating contacts in Mailchimp's flat audience model.

Active subscriptions map to Mailchimp merge fields: plan name (PLAN_NAME), billing interval (BILLING_CYCLE as 'monthly', 'annual', etc.), current MRR (CURRENT_MRR as numeric), subscription status (SUB_STATUS as 'active', 'trialing', 'canceled'), and subscription start date (SUB_START as date). Canceled subscriptions are imported with SUB_STATUS='canceled' and unsubscribed date as SUB_END. Trial subscriptions carry SUB_STATUS='trial' and trial_end_date. Billing interval is normalized from ChartMogul's interval_count and interval_unit fields.

ChartMogul Plan definitions (name, amount, currency, interval) attach to Subscriptions. We map the plan name to a Mailchimp tag (plan_<planname_slug>) and store plan amount and currency as merge fields (PLAN_AMOUNT, PLAN_CURRENCY). If the customer has multiple plans across different billing sources, all applicable plan tags are applied to the single Mailchimp contact. Currency is preserved as a merge field; multi-currency customers note that Mailchimp does not natively support multi-currency segmentation.

Invoice records (amount, date, status, line items) are too granular for Mailchimp's contact model. We generate a structured note per contact listing recent invoices: date, amount, status (paid/outstanding). This preserves billing history in the contact record without exceeding Mailchimp's note length limits. For contacts with fewer than five invoices, full detail is included; for accounts with extensive history, we include the last 12 invoices as a summary. Invoice PDFs do not migrate to Mailchimp; we recommend storing them in a linked document store and referencing URLs in the contact note.

ChartMogul custom attributes are key-value pairs on parent Customer records. We create corresponding Mailchimp merge fields (max 40 characters per field name, uppercase alphanumeric). Date attributes, numeric attributes, and boolean attributes map to Mailchimp DATE, NUMBER, and PHONE field types respectively. String attributes with fewer than 255 characters become text merge fields. Attributes with more than 20 distinct values are converted to tags rather than merge fields to avoid schema bloat in Mailchimp.

ChartMogul tags on parent Customer records migrate 1:1 to Mailchimp tags. Tag counts are preserved. Tags from ChartMogul's CRM sync (e.g., tags synced from HubSpot or Pipedrive) also migrate as Mailchimp tags. Mailchimp applies tags via the Tags API endpoint; we batch tag assignments in groups of 100 to stay within Mailchimp's API limits. Tag names are normalized (lowercased, spaces replaced with hyphens) to match Mailchimp's tag format.

Open and won Opportunities from ChartMogul CRM migrate as merge fields on the linked Contact: opportunity name (OPP_NAME), stage (OPP_STAGE), close date (OPP_CLOSE_DATE), and deal value (OPP_VALUE). Closed-lost opportunities are optionally omitted from migration if the customer prefers a clean contact list; if included, OPP_STAGE='Closed Lost' is set. Opportunity ownership is not migrated because Mailchimp does not have a User object; the owner's name is stored in a merge field (OPP_OWNER) as reference only.