Migrate from Allegory to Mailchimp

Mailchimp text merge fields cap at 255 characters — longer values truncate silently

Mailchimp's Marketing API enforces a 255-character limit on all text merge fields. Allegory fields containing long-form text — notes, descriptions, company addresses, or multi-line custom fields — will be truncated on import with no warning from the API. FlitStack detects fields exceeding 200 characters during the audit phase and either splits the content across multiple merge fields, stores the full value in a flagged comment for manual retrieval, or converts the field to tags. The truncation risk is highest for Allegory notes fields and rich-text custom properties. We surface every field that will truncate before the migration runs so you can decide how to handle each one.

Mailchimp API enforces 10 simultaneous connections and 120-second request timeout

Mailchimp's Marketing API limits clients to 10 concurrent connections per API key and kills requests that exceed 120 seconds. Large Allegory audiences (50,000+ contacts) require batching to stay within these constraints. FlitStack chunks migration batches to 1,000–5,000 records per batch with exponential backoff on 429 responses. The 120-second timeout means long-running list-import operations may need to be split into multiple API calls. We monitor batch responses in real time and retry failed sub-batches. This constraint extends the clock time of large migrations even when the total record count is modest — a 100,000-contact migration may run for 18–36 hours to stay within rate limits.

Mailchimp deduplicates by email address — Allegory contact IDs do not prevent duplicates

Mailchimp uses the subscriber email address as its unique key. If Allegory holds the same person as two separate contact records (e.g., with different company associations or statuses), both will import as separate Mailchimp subscribers rather than merging. Allegory's ID-based deduplication does not translate because Mailchimp has no ID field. FlitStack flags duplicate email addresses during the audit phase and offers three strategies: merge into a single contact (choosing which Allegory status wins), keep both as separate subscribers with tags indicating source record, or suppress the duplicate. The chosen strategy must be confirmed before migration to avoid unexpected audience bloat or undercounting.

Allegory email templates are not transferable to Mailchimp's template format

Allegory's email template format (HTML structures, inline CSS, image embedding) is not directly importable into Mailchimp's template system. Mailchimp supports raw HTML import only for templates built with compatible code — templates using Allegory-specific variables, conditional logic, or non-standard image hosting will not render correctly. FlitStack does not migrate email templates as data objects. We export your Allegory template designs as an HTML reference package so your team or a developer can recreate them in Mailchimp's drag-and-drop or Code Your Own editor. This is a manual step that typically takes 2–4 hours per template depending on complexity. Template recreation should begin during the migration planning phase to avoid a gap between go-live and first send.

Custom objects have no native Mailchimp equivalent and require flattening

Allegory custom objects — membership records, enrollment data, property listings, or any custom relationship object — have no structural equivalent in Mailchimp's model. Each custom object type creates a flat set of merge fields on the primary contact record in Mailchimp, with the custom object type name added as a tag prefix. Relationships between custom objects and standard records (Contact-to-Custom Object lookups) cannot be preserved as relationships in Mailchimp — they become tags on the associated contact. FlitStack surfaces every custom object type during the audit, generates the merge field plan for each, and flags any custom object that requires a manual review step because its relationship cardinality cannot be auto-resolved. Custom object data that does not attach to a primary contact is stored as a JSON-serialized text blob in a dedicated merge field for manual extraction if needed.