Moving an entire list of tens or hundreds of thousands of contacts is a different job from a quick Backfill, so it has its own tool. Migrate runs in the background, a batch at a time, and keeps going while you get on with your day.
Where to find it:
A Migrate button sits next to Backfill on every bridge whose source is one of the built in email apps.
Starting a migration:
- Click Migrate on the bridge row.
- Read the confirm box. It explains the move runs in the background, a batch at a time, keeps going on its own, and is paced so a very large list takes hours.
- Click OK. The row gains a Migration panel.
You can close the page. The migration carries on.
How it works:
Each step reads a batch of 100 contacts from the source and sends them through the bridge, then the next step follows about a minute later. A 25,000 contact list therefore moves over several hours. The pace is on purpose: email apps can suspend an account for a sudden bulk import, so a migration drips rather than floods.
Watching and controlling it:
The Migration panel on the row shows the state and the counts, for example Running, 11400 contacts done of 24850, 11262 sent, 131 skipped, 7 failed, with a progress bar. While the page is open it refreshes every few seconds.
- Pause stops after the current batch. The button becomes Resume.
- Resume carries on from where it stopped.
- Cancel stops the migration. Contacts already moved stay where they are.
- When it finishes, Cancel becomes Clear, which removes the finished panel.
Nothing is lost and nothing is sent twice:
The position only moves past contacts that were processed. If a batch is interrupted, by a timeout or a server restart, the next batch starts from the same place. Anyone already moved is recognised and skipped, so you can pause, cancel and start again as often as you like.
Your Activity Log stays readable:
A migration records only problems in the Activity Log, not a row for every contact, so moving 100,000 people does not bury everything else. A summary of each batch goes to the Diagnostics debug log instead.
A real example:
yoursite.com's Newsletter to beehiiv bridge forwards new Mailchimp subscribers. For the 24,850 people already on the Mailchimp list, the owner clicked Migrate in the morning. By lunchtime the panel read 11,400 done, 11,262 sent, 131 skipped and 7 failed, with the bar a little under half way.
Choosing between the two:
- Backfill for a few hundred or a couple of thousand people, when you want it done while you watch.
- Migrate for a really big list, or whenever you want to start it and walk away.
If the source app cannot be read in pages, Migrate says so and suggests Backfill.
Planning a big move:
- Build the bridge and test it with Send live test.
- Decide whether the destination needs a drip. For a fresh account it usually does.
- Start Migrate in the morning, so you can check progress during the day.
- Keep the bridge enabled afterwards, so new subscribers keep flowing.
How long it takes:
At 100 contacts a step and about a minute between steps, a migration moves roughly 6,000 contacts an hour when your site's checks run on time. A list of 25,000 therefore takes around four to five hours, and a list of 100,000 most of a day.
Tips:
- Put a drip on the destination too if the account is brand new.
- Check the skipped and failed counts in the Activity Log and Diagnostics when it finishes.