Sending a new batch of contacts into an email sequence slowly is a sensible habit. A few each day keeps the sending steady and gives you time to watch how people respond. So it is a nasty surprise when you import a fresh group, plan to release them over two days, and find they have all received the first email already.
We ran into exactly this while running a welcome email sequence for a client in Brevo, the email platform. Nothing was broken. The sequence was doing precisely what it had been told to do. The catch was that it had been told two different things.
What Actually Happened
The welcome sequence had two separate ways in. One started the sequence for anyone added to it by hand. The other started it for anyone who was added to a particular contact list. The plan was to import the new contacts into that list, then add a first batch by hand that day and the rest the next.
The new contacts were imported into the list the sequence watches.
The list rule fired for every new contact right away and started the sequence for all of them.
Everyone imported got the first email that same day.
Adding the first batch by hand afterwards changed nothing, because they were already in.
We confirmed it on the sequence's own statistics page, which shows how many people came in through each way in. The list rule had brought in every one of the new imports, and the first email step showed the whole list, not the smaller group we meant to send to.
One detail worth knowing: the list rule did not go back for people who were already on the list before. It only fired for people added afterwards. But for those, it fired immediately, and an import counts as adding them.
Why a Slow Rollout Quietly Fails
If the list you import into is connected to a live sequence, there is no pause between "they are on the list" and "they have been emailed". Your plan to release people by hand never gets a chance to run. You only find out once the emails have gone.
What we expected
- Import the new contacts into the list
- Nothing happens until we add people by hand
- A first batch starts today, the rest tomorrow
What actually happened
- Import the new contacts into the list
- The list rule starts the sequence for all of them at once
- Everyone gets the first email the same day
Two Ways to Keep Control
If you want new contacts to enter a sequence in steady batches, pick one of these before you import anything.
Turn off the "contact added to list" starting step in the sequence before you import. Then add people by hand in the batches you planned. Switch the rule back on only once everyone is caught up, or leave it off if you want every future contact added by hand too.
Import the new contacts into a separate holding list that is not connected to any sequence. Then move a batch across to the real list each day. Each batch starts the sequence when it arrives, and the rest wait safely.
Check every way in first: Before you trust that adding people by hand is the only way into a sequence, open its builder view and look at every starting box that feeds into it. A list rule sitting elsewhere in the same sequence can skip your plan entirely.
Common Questions
Why did everyone I imported get my welcome email the same day?
Your email sequence was most likely set to start whenever a contact is added to a certain list. That starting rule fires the moment anyone new lands on the list, including a whole spreadsheet you import in one go. It does not wait for you to add people by hand, so everyone you imported starts the sequence straight away.
Does it also email the people who were already on the list?
No. In the case we worked through, the list rule did not go back and pick up people who were already on the list before it was switched on. It only fired for people added after that, but it fired for them right away.
How do I add new contacts to an email sequence a few at a time?
Either switch off the list starting rule before you import and add people by hand in batches, or import everyone into a separate holding list that is not connected to any sequence and move a batch across to the real list each day. Before either, open the sequence's builder view and check every way people can enter it.
Key Takeaways
- A sequence set to start when someone joins a list will start the moment you import new contacts into that list.
- Adding a batch by hand afterwards does nothing if the list rule already brought them in.
- For a slow rollout, switch the list rule off before importing, or import into a holding list and move people across in batches.
- Always check every way into a sequence in its builder view before you import.