Deltek and Mailchimp integration

What moves between them

The main flow runs from Deltek Vantagepoint into Mailchimp. ml-connector reads Vantagepoint contacts and the client firms they belong to, then writes each contact into a Mailchimp audience as a list member, mapping name, email, firm, and title into the audience merge fields. A return flow reads Mailchimp subscriber status and campaign report engagement and updates the matching Vantagepoint contact or activity, so the firm sees who is subscribed, who unsubscribed, and who opened a campaign. Reference data such as audience tags and merge field names is aligned first so every member write lands on a field that already exists. Mailchimp holds no finance data, so ml-connector never moves invoices, payments, or GL entries between the two systems.

How ml-connector handles it

ml-connector stores both credential sets encrypted. On the Deltek side it accepts the full tenant deltekfirst.com URL, database name, and password-grant credentials per customer, refreshes the bearer token before it expires, and pages through the contact and firm hubs because Vantagepoint webhooks are unsigned and not trusted for sync triggers. On the Mailchimp side it sends the API key over HTTP Basic auth or a non-expiring OAuth2 token, resolves the data center prefix once at connection time so calls hit the correct region, and pages through members with offset and count until total_items is reached, keeping inside the ten-connection limit. Each Vantagepoint contact is upserted into the audience with HTTP PUT keyed on the lowercased email, which is idempotent, so a contact re-read through Deltek paging is never duplicated; firm and contact fields map to the audience merge fields, which are aligned first. Mailchimp marks bounced or complained addresses as cleaned and rejects writes that try to re-subscribe them, so ml-connector records that status against the Vantagepoint contact rather than retrying. Mailchimp returns HTTP 429 when too many connections are open, so ml-connector backs off and retries, and large initial loads use the Mailchimp batch endpoint. Every record carries a full audit trail and can be replayed if a downstream call fails.

A real-world example

A mid-sized architecture and engineering firm with around 200 staff runs Deltek Vantagepoint for project accounting, CRM, and proposals, and uses Mailchimp to send newsletters and project announcements to clients and prospects. Before the integration, a marketing coordinator exported contacts from Vantagepoint to a spreadsheet every few weeks and re-imported them into the Mailchimp audience by hand, which left the list stale, missed new contacts added by project teams, and kept unsubscribes invisible to the people in Deltek who still emailed those clients. With Deltek and Mailchimp connected, new and updated Vantagepoint contacts appear in the audience within the sync window, and subscriber status flows back so the firm stops contacting people who opted out. The manual export and re-import step is gone.

What you can do

• •Sync Deltek Vantagepoint contacts and client firms into a Mailchimp audience as list members on the schedule you set.
• •Map Vantagepoint firm and contact fields to Mailchimp audience merge fields, aligned before the first write.
• •Read Mailchimp subscriber status and campaign engagement back into the matching Vantagepoint contact or activity.
• •Bridge Deltek's tenant URL and password-grant token to Mailchimp's API key or non-expiring OAuth2 token, resolving the data center prefix at connection time.
• •Upsert members by email to avoid duplicates, honor cleaned addresses, and carry retries, error replay, and a full audit trail on every record.

Questions

Which direction does data move between Deltek and Mailchimp?

The main flow is Deltek Vantagepoint into Mailchimp. Contacts and client firms move from Vantagepoint into a Mailchimp audience as list members, and a return flow reads subscriber status and campaign engagement back into the matching Vantagepoint contact. Mailchimp holds no finance data, so ml-connector never moves invoices, payments, or GL entries between the two systems.

Can Mailchimp receive invoices or other financial records from Deltek?

No. Mailchimp is an email marketing platform and has no general ledger, invoice, vendor, or purchase order objects. What it does manage is audiences, list members, campaigns, and engagement reports, so ml-connector maps the contact and firm side of Deltek into Mailchimp and leaves accounting data in Deltek where it belongs.

What stops a Deltek contact from being added to Mailchimp twice?

Mailchimp identifies a list member by the lowercased email address, and a PUT to that member is an upsert that adds or updates in place. ml-connector keys each Vantagepoint contact on its email and uses that idempotent PUT, so re-reading the same contact through Deltek's page-based paging never creates a second member. Addresses Mailchimp has marked as cleaned are recorded against the Vantagepoint contact rather than re-subscribed, since Mailchimp rejects those writes.