Company-Level CRM Audience Sync Integration (HubSpot & Mailchimp)

The CRM Audience Sync integration pulls your contacts from your CRM into Letterhead — no manual imports.

Overview

• Available CRMs: HubSpot and Mailchimp — set up differently, from different screens.
• One-way sync into Letterhead: your CRM is the source of truth. Changes to First Name, Last Name, and Email flow from your CRM into Letterhead — not the other way around.
• Channel mapping (Mailchimp): choose which newsletters (channels) use the connection, then choose which parts of the one connected Mailchimp list each newsletter sends to — the options are that list’s saved segments and interest groups — or apply the same selection to every selected channel at once. HubSpot has no separate mapping step: once connected, contacts sync automatically by matching email address.
• Different refresh patterns per CRM: HubSpot re-syncs on demand (when you connect or manually re-sync); Mailchimp syncs on a schedule. Neither is instant or continuous.
• HubSpot engagement sync: engagement from newsletters sent to HubSpot contacts (opens, clicks, deliveries, bounces, subscription status, and tags) flows back to the matching HubSpot contact.

Roles and prerequisites

• Setting up or deleting a CRM integration is an admin task, since it applies across the whole company. If you don’t see the option, ask an organization administrator.
• HubSpot needs nothing prepared ahead of time — you’ll authorize the connection from inside your HubSpot account during setup.
• Mailchimp needs your Mailchimp account’s server prefix (the short code in your Mailchimp login URL, e.g. us21), an API key from your Mailchimp account, the List Id of the audience you want to sync, and a reply-to email address. All four are required — the sending setup guide covers where each one goes.
• Company account — CRM integrations are only available on company-level accounts; your CSM can confirm whether yours qualifies.

HubSpot setup

1. Connect your account — open Integrations, select HubSpot, and click Connect. You’ll be sent to HubSpot to authorize Letterhead; no API key or server prefix to enter.
2. That’s it — once authorized, Letterhead starts pulling your HubSpot contacts in automatically, matched by email address. There’s no channel or field mapping step to complete.
3. Re-sync anytime — click Re-sync now on the connected integration to bring everything current on demand (HubSpot doesn’t sync continuously in the background).

When you connect, Letterhead creates custom fields on your HubSpot contacts to hold engagement data — opens, clicks, deliveries, bounces, subscription status, and tags from newsletters you send.

Mailchimp setup

Mailchimp isn’t connected from the company Integrations page. It uses the same connection you set up for sending through Mailchimp, so there’s nothing separate to configure for the sync — go to Settings → Sending at the company level, choose Add a New Connection, and select Mailchimp.

Create newsletters in Letterhead while sending through your own ESP walks the setup through end to end: the connection details it asks for, choosing which newsletters use the connection, and choosing which segments or interest groups each newsletter sends to.

Managing the integration

• HubSpot — pause or delete: in Integrations, select HubSpot, choose More Options → Deactivate Integration, and confirm by entering the text prompt.
• Mailchimp — update your connection details, the newsletters using it, or its audience mapping any time from Settings → Sending → Mailchimp.
• Reconnection: if you disconnect, previously synced data remains, but syncing stops until you reconnect.

Behavior and edge cases

• One-way sync (contacts): contacts flow from your CRM into Letterhead. Editing a contact in Letterhead doesn’t change anything back in HubSpot or Mailchimp.
• HubSpot engagement flows back: opens, clicks, deliveries, bounces, subscription status, and tags from newsletters sent to HubSpot contacts appear on the matching contact in HubSpot.
• HubSpot syncs on demand — when you connect the integration, and again whenever you trigger a re-sync. It doesn’t watch for live changes in HubSpot.
• Mailchimp syncs on a schedule in the background. It’s a read-only view of your Mailchimp audience — Letterhead never writes back to Mailchimp.
• Limited contact fields: only First Name, Last Name, and Email are synced.
• HubSpot lists as tags: each HubSpot list arrives as a tag in Letterhead, which you can use to build segments.
• Email matching: contacts are matched by email address. Anyone already in Letterhead keeps their existing source.

Need help?

See Working in Integrations for everything the Integrations area covers, or contact support.