Delta Sync

What Is Delta Sync?

After a bulk migration, users may continue receiving email and making changes on the source platform during the DNS transition period. Delta sync continuously syncs new and modified items from source to destination.

Setting Up Delta Sync

1. Complete your bulk migration
2. Go to the migration job → Delta Sync tab
3. Click Create Delta Sync Job
4. Configure the sync interval (e.g., every 15 minutes), data types to sync, and users (auto-inherited from the parent migration job)

How It Works

Delta sync checks for items created or modified since the last sync, migrates new items to the destination, uses duplicate prevention to ensure no duplicates, and repeats at the configured interval. The first run uses the parent migration job's completion timestamp as the starting point, ensuring zero data gap.

Cutover Mode

For planned DNS cutover events:

1. Enable Cutover Mode on the delta sync job
2. Set your Cutover Date (when DNS will switch)
3. Set the Window (default: 48 hours after cutover)
4. Delta sync automatically stops after the window expires

The 48-hour window catches any email delivered during DNS propagation.

Monitoring

Delta sync jobs appear in the Migrations list with a sync icon. Each run shows items synced, skipped, and failed. Celery Beat schedules runs automatically — no manual intervention needed.

Trigger All

For cutover night, use the Trigger All button or API endpoint to force an immediate sync across all active delta sync jobs simultaneously.