Constant Contact Integration

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Klaviyo's Constant Contact integration is designed to help you move from Constant Contact to Klaviyo. We don't recommend using both platforms at once other than during the interim period as you make the switch.

We also have a general checklist that covers how to completely migrate over to Klaviyo from a different Email Service Provider (ESP) here.

From Constant Contact, Klaviyo pulls in the following data:

  • When someone received, opened, or clicked a particular email
  • A list of emails who have unsubscribed or bounced
  • Existing lists in Constant Contact (you can choose to create Klaviyo lists from your Constant Contact lists)

If you delete people in Constant Contact, they will not also be deleted in Klaviyo. However, if people are added to a Constant Contact list that is synced with a Klaviyo list, they'll be added to Klaviyo within an hour.

Create a Mashery Account

Start by creating a Mashery account, or logging in to your existing account if you already have one.

If you're creating a new account, use your own name and email address.

You will receive an email from Mashery. Open this email and click the link to confirm your new account.

Register an Application and Obtain an API Token

Next, register a new application in order to obtain an API token you can use to pass your data from Constant Contat to your Klaviyo account.

  1. Navigate to the following url:
  2. Name your application. We recommend that you do not reference Klaviyo in your application name.
  3. In the box titled "Select which Web APIs this application will use", ensure that Issue a new key for Constant Contact API and Standard API Access are both selected.
  4. Agree to the terms of service and click Register Application.
  5. You will use both the application Key and Secret provided on the next page to integrate your Klaviyo account with Constant Contact.  These can be retrieved later by navigating to and selecting the correct application.

Update your OAuth Redirect URI

Next, update your OAuth Redirect URI so your application can connect with your Klaviyo account.

  1. Navigate to and locate the application you just registered in the steps above. Click Edit.
  2. On the following page, paste into the Redirect URI for OAuth Calls field, highlighted in green below.

Now your application is ready to connect with Klaviyo.

Add Your Integration in Klaviyo

Use the Key and Secret from the application you registered above to connect your Constant Contact account to your Klaviyo account.

  1. Navigate to
  2. Paste your Key and Secret into the correct fields and click Connect to Constant Contact.
  3. You will be redirected to Constant Contact. If you are not already signed in, you will be prompted to enter your username and password.
  4. Click Allow to permit Klaviyo to access your Constant Contact data. You should see the name of the application you registered.
  5. You will be redirected back to Klaviyo, and will see a confirmation message at the top of the page.

This completes the integration. Klaviyo will begin to sync your contacts and the past 90 days of your event data.

Monitor the Klaviyo Sync

Once you've connected Klaviyo with Constant Contact, data will start syncing within a minute or two. If you navigate to the Metrics tab in your Klaviyo account, you should see a several metrics for Constant Contact data (received email, opened email, and clicked email) each with a Constant Contact icon next to it.

While you may see the Received Email (Constant Contact) metric in your account as showin in the screenshot above, Klaviyo does not currently record any of these events.

Once your sync is complete, you'll see Constant Contact on your Enabled Integrations list.

Frequency of the Klaviyo Sync

Klaviyo will run an initial sync of all historical data as soon as you click Update Constant Contact SettingsMoving forward, however, Klaviyo will sync data on an ongoing basis once an hour.

Best Practices

To ensure that you maintain good deliverability, you should only send your first few email campaigns to an engaged segment of your list(s) from Constant Contact. Since you'll have open and click data from Constant Contact, you'll be able to use this to segment your list.

If you email your subscribers more than once a week, you should send your first week of email campaigns to an engaged segment defined as follows:

Opened Email at least once in the last 120 days
Clicked Email at least once in the last 120 days

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