How to import data from Postscript to Klaviyo

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You will learn

Learn how to import your data from Postscript to Klaviyo for your SMS program. When migrating from Postscript, you can upload your existing list of SMS subscribers to Klaviyo to start building out your SMS marketing strategy right away.

Importing your SMS contacts allows you to centralize customer data so you can leverage Klaviyo’s robust analytics and tailor your customers' experience through the use of SMS-integrated flows, emails, and push notifications.

Before you begin

Before you start the import process, you must: 

  1. Enable SMS in Klaviyo
  2. Set up you sending numbers for all countries you want to send to

Otherwise, consent for your imported customers will not be stored. 

Check this guide on migrating from another SMS provider for instructions.

Export SMS subscribers from Postscript

Before you begin migrating your SMS contacts from Postscript into Klaviyo, it's important to distinguish between subscribers who have opted-in to SMS messaging and those who have not. It is against Klaviyo's Terms of Service and TCPA laws to market to contacts who have not explicitly opted-in to receive SMS communication from your business.

Klaviyo identifies opt-in subscribers as those who have a phone number and an SMS Consent Timestamp associated with their profile. In Postscript, this timestamp may be assigned to the field subscriber_created_at_utc in your export file. Klaviyo will only send SMS messages to contacts who have both a phone number and an SMS Consent Timestamp stored within their Klaviyo profile.

Postscript allows you to export a list of all SMS subscribers directly from your account into a CSV file. This list will simplify the import process into Klaviyo.

  1. To begin, log in to your Postscript account or navigate to it from your ecommerce store’s connected apps.
  2. From the Postscript dashboard, click your account name dropdown in the upper right corner and select Account.
    Menu open with Account outlined in red
  3. On the Account page, scroll down to the Exports section.
  4. Select Subscriber Export from the dropdown menu and then click Export. Postscript will process your export request and alert you when the subscriber list is complete and ready for download. Keep in mind that the larger your list of SMS subscribers, the longer the export will take to generate.
    Exports dropdown with subscriber export chosen and export with blue background
  5. When your subscriber list is ready, click Go To Reports to be redirected to the Reports page where your list is available for download.
    Reports page with Active Subscriber Export in list and Download in blue
  6. Your newly exported list will appear under Report Name as Active Subscribers Export along with a download link and timestamp. If you have more than one subscriber export, use the timestamp provided to identify the most recent export. Click Download to retrieve the exported CSV file from Postscript.

Format subscriber list CSV

You should carefully format your CSV file before importing it into Klaviyo. This will ensure that your contacts are imported smoothly and accurately. Postscript’s exported CSV file includes all the columns you will need, along with some additional columns you may choose whether or not to import. 

  1. You will likely want to include these columns in your import:
    • First_name
    • Last_name
    • Email
  2. If the following columns appear, you may wish to either remove them from your import, or map them to new fields in your Klaviyo account. Consider whether or not these fields are valuable to you, and remove the columns if you choose.
    • Customer_id
    • Last_keyword_subscribed_to
    • Automation_and_campaign_texts_sent_count
  3. The phone number column is required to import your SMS contacts. Check the format of the phone numbers in your CSV file. Phone numbers must be in one of the following formats:
    • E.164 (e.g., +12345678910)
    • RFC966 (e.g., +12-34-567-8910)
    • E.123 national (e.g., 12345678910) 
    • International formats (e.g., +12 345 678 910)
  4. Add in a column for the country. If you are sending in the United States, assign the value USA to all rows. Otherwise, check the country code of your opted-in subscribers and add a country value, such as UK or Australia, that corresponds to their country code. Note that you can only import consent for countries where Klaviyo SMS is available.
  5. Klaviyo requires an SMS Consent Timestamp column, so you will need to rename the appropriate column heading. Locate the column heading subscriber_created_at_utc and delete the text, renaming it SMS Consent Timestamp. Doing so allows your import to automatically map the values to the correct field in Klaviyo. Timestamps need to be specifically formatted or Klaviyo will not recognize them as timestamp fields. Postscript exports timestamp data in the format MM/DD/YYYY HH:MM:SS by default. However, the format MM/DD/YYYY HH:MM will also import correctly. 

Import subscriber list to Klaviyo

After you've formatted your export data, you can import it into a Klaviyo list.

  1. To begin, log in to your Klaviyo account and navigate to Lists & Segments.
  2. Click Create List / Segment in the upper right corner to create a new list for your SMS Subscribers. On the next page, select List.
  3. Give your new list a name, such as Postscript SMS Subscribers and click Create List.
    List builder in Klaviyo showing list named Postscript SMS Subscribers
  4. Once your new list is created, click Upload Contacts to add your SMS subscribers via import. Drag and drop your CSV file into the field provided, or select it from your computer to upload your contacts.
  5. After selecting your file, Klaviyo will process the import and display a green loading bar with the text Uploading and validating file… If any required columns are missing, Klaviyo will alert you with an error message.
  6. If you would like to add the contacts to an existing list, locate the list where you'd like to upload your contacts. Then, click the menu to the right of the list and select Import Data. Drag and drop your CSV file into the field provided to upload your contacts. For more detailed instructions on adding new contacts to a list, head to our article on creating and adding contacts to a list.
  7. Whether you create a new list or update an existing list, you will be prompted to review field mapping before Klaviyo begins the import. Carefully review each import field/corresponding Klaviyo field, and modify them as needed. By default, all identified fields are included in the import. You can omit a field from the import by unchecking the box to the right of the field name.
  8. Here is an example of field mapping for an SMS contacts import from Postscript:
    Import review page showing some fields unmapped in red
  9. Import fields that are not automatically matched to a Klaviyo field are marked as Unmapped. If you try to import an unmapped field, an error message will appear, prompting you to map the field. From the dropdown, select an existing Klaviyo field name or create a custom field by typing a name into the blank entry field. To the right of the field name, select a data type from these options: String, Boolean, Numeric, Date, or List. If you're unsure of the data type, head to our article on data types in Klaviyo.
  10. When you are satisfied with the field mapping, click Import Review on the upper right-hand corner of your screen.
  11. Review your selections, taking special note of SMS Consent verification. When finished, click Start Import.
    Ready to import? page with start import with blue background

Your import will begin shortly. Depending on the length of your contact list, the import may take some time. You can stay on this page to watch the upload progress, but it is not necessary. Klaviyo will also send you an email confirmation as soon as the import is complete.

After the import finishes, you will see a summary of the completed import which includes a report of any skipped records. If your CSV file contains improperly formatted data, those fields may fail to import properly. When this occurs, you can download a report of the skipped records, resolve any formatting issues, and retry importing those records.

Import details with yellow callout showing 4 records skipped

For a deeper dive into importing contacts, head to our article on migrating existing subscribers and unsubscribes into Klaviyo.


You've now learned how to import data from Postscript to Klaviyo.

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