Importing Contacts into Klaviyo - Startup

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If you’re just getting started with Klaviyo, you may still have subscribers in a previous email service provider (ESP) like MailChimp or Constant Contact. While Klaviyo will automatically sync contacts from your ecommerce integration, you may also have a newsletter list that you want to import. Any contacts that are synced through your ecommerce integration do not need to be manually imported.

If you haven’t done any email marketing before and don’t have an existing list of contacts, you can skip this step and go straight to setting up your signup forms and start organically growing your list.

Integrate with Your Previous ESP

If you are coming over from another ESP, you’ll want to migrate your existing contacts into Klaviyo so you can start sending them targeted emails. Klaviyo has several pre-built integrations with other ESPs. If you see your previous ESP in the list below, go ahead and add this integration from the Integrations tab in your account. The docs below will outline the import steps specific to your integration:

This is an important step because the it will allow you to sync not only email addresses, but also historical data, such as open and click data. This will allow you to build a segment of engaged subscribers. Sending to these subscribers is a crucial first step, as it helps you maintain good deliverability and strengthen your sender reputation.

Import Your Contacts as a CSV

If you aren’t able to sync contacts from one of the integrations listed above, you can manually import your contacts into Klaviyo as a CSV. Whenever uploading a list, please ensure that all the contacts on it have opted in to receive marketing emails.

Formatting Your CSV

It is important to note that your CSV must have a column labeled “Email” or “Email Address” in order to successfully upload contacts. In addition to this column, you have the option to add other columns, such as First Name, Last Name, and any custom properties you would like to attach to subscribers’ profiles (for example, gender). Below is an example of how your CSV should be formatted:


Please note the timestamp format in the Birthday column. If you intend on uploading any timestamps, they must be in this format in order for Klaviyo to identify them as a date. If you are using Excel, you can prevent these cells by autoformatting by changing the format to “Text.”

Upload Your CSV

First, create a new list by navigating to the Lists & Segments tab and selecting Create List/Segment. Once you give your list a name, you’ll have the option to upload a CSV to populate this list.


Upload Suppressed Contacts to Your Suppression List

Once you've uploaded your list, you'll want to upload any contact addresses that have unsubscribed, hard bounced, or marked your emails as spam to your account's suppression list. This will ensure that you don't accidentally email them and harm your deliverability.

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