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MailChimp Integration

Connect OneTap Login to MailChimp to automatically add Google sign-in users to your email list.

Prerequisites​

  • MailChimp account (free tier works)
  • At least one audience (list) created
  • API key generated

Step 1: Get MailChimp API Key​

1.1 Access API Keys​

  1. Log into MailChimp
  2. Click your profile icon (bottom left)
  3. Click Profile
  4. Click Extras > API keys

1.2 Create API Key​

  1. Scroll to "Your API keys"
  2. Click Create A Key
  3. Name it "OneTap Login"
  4. Copy the key immediately
Save Your Key

The API key is only shown once. Copy it immediately and store securely.

API Key Format:

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx-us1

The suffix (us1, us2, etc.) indicates your data center.

Step 2: Get Audience ID​

2.1 Find Your Audience​

  1. Go to Audience > All contacts
  2. Click Settings
  3. Click Audience name and defaults

2.2 Copy Audience ID​

  1. Scroll to "Audience ID"
  2. Copy the ID

Audience ID Format:

a1b2c3d4e5

Step 3: Configure OneTap Login​

3.1 Access Settings​

  1. Go to WordPress Admin
  2. Navigate to Settings > OneTap Login
  3. Click Integrations tab
  4. Find Email Marketing section

3.2 Enter Credentials​

MailChimp API Key Field

  1. Enable Email Marketing: Toggle on
  2. Provider: Select MailChimp
  3. API Key: Paste your API key
  4. List ID: Paste your Audience ID

3.3 Test Connection​

MailChimp Test Connection

  1. Click Test Connection
  2. Verify "Connection successful" message
  3. Click Save Changes

Configuration Options​

Double Opt-in​

Enable DOI in MailChimp:

  1. Go to Audience > Settings
  2. Click Audience name and defaults
  3. Under "Form Settings"
  4. Enable Enable double opt-in

OneTap Login respects this setting automatically.

Tags​

Add tags to new subscribers:

Setting: Tags to add Example: google-signup, new-customer

Tags are created automatically if they don't exist.

Merge Fields​

Map user data to MailChimp merge fields:

OneTap FieldMailChimp Merge Field
First NameFNAME
Last NameLNAME
EmailEMAIL (automatic)

Standard merge fields (FNAME, LNAME) are used automatically.

Subscriber Status​

With Double Opt-in Enabled​

New subscriber → status: "pending"
        ↓
Confirmation email sent
        ↓
User clicks confirm
        ↓
Status: "subscribed"

With Double Opt-in Disabled​

New subscriber → status: "subscribed"

Verification​

Check Subscriber Added​

  1. Go to MailChimp Audience > All contacts
  2. Search for the test email
  3. Verify subscriber exists
  4. Check tags and merge fields

Check Activity Log​

In MailChimp:

  1. Go to Audience > All contacts
  2. Click on subscriber
  3. View Activity tab
  4. See subscription source

API Rate Limits​

MailChimp limits:

  • 10 concurrent connections
  • No hard request limit (fair use)
  • Batch operations for high volume

OneTap Login subscribes one at a time (per registration).

Error Messages​

"API Key Invalid"​

Cause: Wrong or expired API key.

Solution:

  1. Generate new API key
  2. Copy complete key including -usX suffix
  3. Update in OneTap settings

"List Does Not Exist"​

Cause: Wrong Audience ID.

Solution:

  1. Verify Audience ID in MailChimp settings
  2. Check for typos
  3. Ensure audience isn't archived

"Member Exists"​

Cause: Email already in audience.

Solution: This is normal for returning users. OneTap skips existing subscribers.

"Compliance State"​

Cause: Email is on compliance hold.

Solution: Check MailChimp compliance settings or contact MailChimp support.

MailChimp-Specific Features​

Groups​

To add subscribers to a specific group:

  1. Get group ID from MailChimp
  2. Configure in OneTap settings (if available)
  3. Or use MailChimp automation to assign

Automations​

Trigger automations on subscription:

  1. In MailChimp, create automation
  2. Set trigger: "Someone subscribes"
  3. Filter by tags (e.g., "google-signup")

Segments​

Create segment of Google users:

  1. Go to Audience > Segments
  2. Create segment
  3. Condition: Tags > is > google-signup

Integration Code​

How OneTap Calls MailChimp​

// Simplified example
$response = wp_remote_post(
    "https://{$dc}.api.mailchimp.com/3.0/lists/{$list_id}/members",
    [
        'headers' => [
            'Authorization' => 'Basic ' . base64_encode("user:{$api_key}")
        ],
        'body' => json_encode([
            'email_address' => $email,
            'status' => 'pending', // or 'subscribed'
            'merge_fields' => [
                'FNAME' => $first_name,
                'LNAME' => $last_name
            ],
            'tags' => ['google-signup']
        ])
    ]
);

Troubleshooting​

Connection Test Fails​

  1. Verify API key format (includes -usX)
  2. Check API key hasn't been deleted
  3. Verify account is active
  4. Try generating new API key

Subscribers Not Appearing​

  1. Check DOI: User may need to confirm
  2. Verify correct audience selected
  3. Check MailChimp cleaned/bounced list
  4. Review OneTap debug logs

Tags Not Applied​

  1. Verify tag names in settings
  2. Check for special characters
  3. Tags are created if they don't exist

Best Practices​

Do's​

  • Use double opt-in for GDPR compliance
  • Tag Google signups for segmentation
  • Set up welcome automation
  • Monitor subscription rates

Don'ts​

  • Don't disable DOI for EU audiences
  • Don't use API key in public code
  • Don't ignore bounce/complaint rates

Next Steps​