How syncing works

Once you’re connected, the extension keeps Mailchimp in step with your store on its own, in the background, minute by minute. Here is what moves, and the one thing worth understanding before it does.

What syncs, and when

Everything below syncs continuously, after an initial catch-up during setup:

• Newsletter subscribers: opt-ins and opt-outs, within minutes.
• Orders: new orders in real time; past orders once, during setup.
• Abandoned carts: carts sync while shoppers build them, so Mailchimp can start recovery the moment one goes quiet.
• Products: catalog changes as they happen, so campaign recommendations stay current.

And products means the whole catalog: all six native Magento product types (Simple, Virtual, Downloadable, Bundle, Grouped and Configurable), Adobe Commerce gift cards with dedicated support, and any custom type a third-party extension adds, synced with a best-effort standard payload built from the fields every product carries. Orders and carts containing them sync normally with full, accurate totals, and an open-amount gift card is reported at the exact amount the shopper chose.

Behind those bullets are two avenues, with the same names you will see across the Dashboard and Cron Monitor. Boost carries what is happening right now: a new order, a live cart, an opt-in, a product edit. Backfill carries history: the past orders, customers and catalog you chose at setup. Both run on the same engine, at the same pace, every minute; the only difference is priority. New activity always goes first, so a big history import never delays a fresh order.

Built for throughput

Syncing is not one record at a time. Mailchimp allows ten simultaneous connections per account; the extension takes eight of them and load-balances your queue across all eight lanes at once, using what Mailchimp offers while always leaving headroom. Four habits make those lanes count:

• Nothing waits on anything. If an order reaches the front of the queue before its products or its customer, the extension syncs those first, in the same pass, on its own. No stuck records, no manual ordering.
• Nothing unchanged is ever sent. Every record is fingerprinted before it goes; if nothing changed, nothing is sent. On a typical day that skips most of the queue outright.
• Nothing slows your store. All of it runs in the background queue, never in your shopper’s page or checkout.
• Nothing burdens your server. Every sync pass runs on a strict time budget and careful memory use, does its work, and hands the server back. Your store stays fast on the days it matters most.

And it is built for the big days. On a Black Friday-sized wave, the extension moves thousands of orders and carts without strain: most reach Mailchimp in real time, and anything that queues behind the wave lands minutes later. It is a good citizen on Mailchimp’s side too: if Mailchimp asks it to ease off, it backs off, retries, and loses nothing.

Record now, work later

When something happens in your store, a new order, a product edit, an opt-in, the extension does one deliberately tiny thing in that moment: it writes a small note in its queue. A single lightweight database write, milliseconds, and the shopper moves on. All the intelligence, building payloads, fingerprinting, resolving dependencies, talking to Mailchimp, runs later in the background lanes, where it can never slow a page. Mailchimp is never called during a shopper’s visit.

Webhooks get the same discipline in reverse. When Mailchimp reports an unsubscribe or an email change, the receiver verifies the message with a secret key, records it, and applies it locally in the same moment: database updates only, milliseconds, and Mailchimp gets its answer immediately. Profile edits take one extra step, reconciled through the queue within about a minute. Either way, no one ever waits on anyone.

The one thing to understand: subscribers vs. customers

The same person can exist in Mailchimp two ways:

• A subscriber opted in to your newsletter: you can send them campaigns.
• A customer placed an order (or left a cart) but never opted in: they are in your audience for their purchase history and segmentation, but you cannot email them campaigns.

Both count the same on your Mailchimp bill. (Mailchimp explains all the contact statuses in its own help.)

One promise runs through all of it: your audience is yours. The extension adds and updates contacts; it never unsubscribes, demotes or removes anyone on its own.

The extension never syncs your whole customer database. Only people who opted in to your newsletter, placed an order or left a cart become contacts.

Choosing your order window

During setup, the wizard asks how far back to import order history: 3, 12, 24, 36 or 48 months, or everything. It recommends twelve months, and that recommendation is worth trusting: campaigns convert on recent behavior. What someone bought this year predicts what they will buy next; what they bought three years ago mostly adds billable contacts who no longer open your emails, and a colder list means weaker engagement and weaker deliverability for everyone else. Twelve months captures your active buyers plus a full holiday season. Go wider only if your product has a naturally long repurchase cycle, think furniture, not fashion.

The window is a filter, not a wall. With the recommended defaults, the import only brings in customers who ordered inside the window; older one-time buyers stay out of your audience, and off your bill, at import time. But they are not forgotten. The moment one of them comes back, placing an order, leaving a cart, even just logging in, the extension syncs them automatically, usually within a minute or two. And they come back whole: their profile lands with lifetime totals, order count and shopping scores computed from their complete purchase history, not just the window. They join as non-subscribed, so they receive order and cart emails but no campaigns until they opt in.

A dormant customer revives the instant they matter again. Until then, they cost you nothing.

Which orders sync

By default, confirmed revenue means processing, complete and closed: that selection decides which historical orders are imported and which orders count toward revenue and lifetime value. New orders sync as they happen and stay updated through every status change. You decide exactly which ones count under Order Statuses to Sync in the Ecommerce Sync settings. The order window for the first sync is the one you chose in the Setup Wizard.

Questions about what synced and when? Troubleshooting covers the common ones, and ebizmarts support is one email away.