Import opt-out lists from Customer.io

First, you'll need to create an app API key in Customer.io. This key will be used later to import all categories and generally unsubscribed customers.

Go to Settings > Account Settings > App API Keys in your Customer.io dashboard.

Click Create New App API Key and give it a descriptive name (e.g. "PostHog Import").

Important: Save this API key securely - you'll need it in step 3. Customer.io will only show it once.

Now you need to export a CSV of people who have opted out of specific categories.

Go to the People page in your Customer.io dashboard.

To filter for people with subscription preferences:

1. Click conditions at the top of the page
2. Select cio_subscription_preferences from the dropdown
3. Choose the exists operator
4. Confirm your choice

This will update the people list in the table below to show only those with subscription preferences.

Now export this data:

1. Click Export to CSV in the top right corner
2. Click Choose attributes
3. Select only these two attributes:
   • cio_subscription_preferences
   • email (make sure it's email and not $email)

Customer.io will send you an email with a download link for the CSV file. Download this file - you'll upload it to PostHog in the next step.

Go to your PostHog app and navigate to Workflows > Opt-out list.

Click Import from Customer.io.

You'll see a two-step import process:

Step 1: Import via API key

Enter the API key you created in step 1. This will import:

• All available categories from Customer.io
• All customers who are generally unsubscribed (not subscribed to any category)

Due to rate limiting, we need to import customers that opted out of certain categories through the CSV.

Step 2: Upload CSV

Once step 1 is completed, you'll be prompted to upload the CSV file you downloaded in step 2.

1. Click Choose file and select the CSV you downloaded from Customer.io
2. Click Upload & process CSV

This will import customers who opted out of specific categories (those with granular subscription preferences).

Once complete, you'll see a success message with a summary of imported opt-outs.

Your Customer.io opt-out lists are now imported into PostHog. These users will automatically be excluded from all future workflow campaigns based on their preferences.