Importing a list does not enroll anyone in a flow. The contacts are added to your Contacts screen, but they will not enter your Welcome Flow or any other flow.
This is deliberate. Flows run on events as they happen, so an import would otherwise drop a whole list into your automations at once. It protects your sending reputation and keeps flows tied to something the contact actually did.
What will not enroll them
A tag column in your import file. Tags applied by an import are written in bulk, and bulk tag changes do not enroll contacts in flows.
The Tags button on the Contacts screen. Selecting several contacts and tagging them works for organising your list, but it will not start a flow either, for the same reason.
Turning the flow on afterwards. A flow only picks up events that happen after it is switched on. Nobody imported earlier will enter it.
What does work: tag one contact at a time
Adding a tag from an individual contact's profile does enroll that contact in a flow that uses the New tag trigger. This is a good fit for a small list, for example contacts you collected at an event. For a longer list, send a campaign instead, covered further down.
Step 1: Build a flow that triggers on the tag
Go to Flows and click New flow, then From Scratch.
Set the trigger to New tag.
Click Add Trigger Filter, choose Added tags, and pick the tag you are going to use.
Add your email and SMS steps, then turn the flow on.
A flow has exactly one trigger. If you want your existing welcome series to run for these contacts, duplicate it and change the trigger on the copy to New tag. Do not change the trigger on your live welcome flow, or it will stop running for new subscribers. See Flow triggers, steps and settings.
Step 2: Import your list
Import the contacts as normal, following Importing a list of contacts. Make sure you map the email and SMS subscription columns, so the contacts arrive with the right consent status.
Every import also creates its own tag, named after the date of the import, for example List import Aug 20 2025. That tag is how you find this batch again later.
Step 3: Add the tag to each contact
Open a contact from the Contacts screen. Under Tags, click Add tag and tick the tag your flow is waiting for. The contact enters the flow straight away. Repeat for each contact you want enrolled.
For a larger list, send a campaign instead
Tagging hundreds of contacts by hand is not realistic, and it is not what flows are for. Send a campaign instead:
Create a segment filtered on the import tag. See What are segments (saved filters)?
Build a campaign with the same content as your flow email.
Send it to that segment.
A campaign sends once to everyone who matches, which is usually what you want for a list you already have in hand.
Flows that were turned off
The same rule applies to a flow that was inactive for a while. When you turn it back on, it does not go back and send to the contacts who qualified while it was off. It starts fresh from the moment it is switched on.
To reach the people who missed it, send them a campaign covering that period.
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