If you've just enabled email activity tracking in Mailchimp for Salesforce, you might notice the initial sync takes much longer than expected. The progress indicator may pause at certain percentages, or it could take hours (or even overnight) before all your email activity data appears in Salesforce. This delay is completely normal and expected behavior.
When you first turn on email activity tracking, the system needs to import all historical activity data within your configured retention period. This one-time backfill process involves processing thousands or even millions of individual activity records (opens, clicks, bounces, unsubscribes), which takes significantly more time than the quick incremental syncs you'll see once the initial import completes.
The Solution
Email Activity Tracking is Not Enabled by Default
Mailchimp for Salesforce does not automatically store email activity data in Salesforce. This is an optional feature you enable through the Mailchimp Settings tab. When disabled, you can still view live email activity through Lightning Components, but the data isn't stored in Salesforce for reporting purposes. The storage warning exists because each email activity record uses approximately 2KB of Salesforce data storage.
Why the Initial Sync Takes Time
When you first enable email activity tracking, the system performs a complete historical backfill rather than just syncing new activity going forward. This involves several technical processes that extend the sync time:
The system retrieves all historical email activity for your campaigns within your configured retention period (for example, the last 90 days or 180 days). If you have high-engagement campaigns or a large subscriber base, this can mean processing hundreds of thousands or even millions of individual activity events.
To stay within Salesforce governor limits, the sync runs in multiple Apex batch jobs. Each batch processes a subset of your campaigns and activity types (opens, clicks, unsubscribes, bounces), and these batches must run sequentially rather than all at once. If you have dozens of active campaigns with significant engagement, you may see 20, 30, or more batch jobs queued and running one after another.
The API callout process itself adds time. For each campaign, the system must make API calls to Mailchimp to retrieve the activity data, page through results, and then create the corresponding Email Activity records in Salesforce.
The Progress Indicator Behavior
During the initial import, you'll likely see the progress indicator pause at certain percentages for extended periods. This is normal. The batch jobs are actively working through your data, but because they process different campaigns and activity types separately, the overall percentage doesn't update smoothly. The system is creating Email Activity records in the background even when the percentage appears stuck.
What to Expect for Timing
For most organizations, the initial import takes several hours. If you have a large volume of campaigns or historical data, it's not unusual for the process to run overnight or even into the next business day. The exact duration depends on your data volume, the number of campaigns, subscriber engagement levels, and your configured retention period.
Subsequent Syncs Are Much Faster
After the initial backfill completes, all future syncs operate incrementally. They only process new or changed activity data since the last sync, which typically completes within minutes rather than hours. This is why the delay you experience during initial setup won't be a recurring issue.
How to Verify the Sync is Working
If you're concerned the sync has stalled, you can verify it's progressing by checking that new Mailchimp Email Activity records are being created in Salesforce. Navigate to the Mailchimp Email Activity object and review recent records by Created Date. Even if the progress indicator hasn't moved, seeing new records confirms the batch jobs are actively running.
If you don't see any new activity records being created for an extended period (several hours with no change), or if you see error messages in the sync status, contact support. We can check the batch job status in your org and confirm everything is processing correctly.
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