Migrate from Sailthru to Klaviyo

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This guide is designed to assist customers in migrating from Sailthru to Klaviyo quickly and safely in time for Black Friday 2019.

While Klaviyo does not have a built-in integration with Sailthru, you can migrate your data over by exporting it from Sailthru and importing it into Klaviyo. Additionally, when you sync your ecommerce store with Klaviyo, customer data will be synced and you will be able to send triggered emails based on onsite activities. This guide will walk you through getting set up with Klaviyo.


Below are the main steps you will need to follow to get your Klaviyo account up and running:

  1. Integrate your ecommerce store.
  2. Migrate your email templates from Sailthru.
  3. Set up key flows.
  4. Upload your engaged contacts from Sailthru.
  5. Set up a dedicated sending domain.
  6. Batch send initial email campaigns to 30-day engaged customers to ensure strong deliverability.
  7. Monitor deliverability performance.
  8. Open up email campaigns to a broader group of engaged subscribers.

Integrate Your Ecommerce Store

If your ecommerce store has been around for over 5 years and you intend on syncing historical purchase data for over 250,000 customers, please reach out to Klaviyo Support before you do so to ensure that your experience is seamless.

Klaviyo has native integrations with several different types of ecommerce platforms, including:

Follow the instructions in the appropriate guide to integrate your store with Klaviyo. If your ecommerce store has been around for over 5 years and you intend on syncing historical purchase data for over 250,000 customers, please reach out to Klaviyo Support first.

Migrate Your Email Templates from Sailthru to Klaviyo 

Klaviyo has an intuitive drag-and-drop template builder that you can use to recreate your Sailthru templates. We recommend using this method to build your templates because it will ensure that they are mobile-optimized, responsive, and easy to edit and iterate on going forward.

However, if you don’t have time to dedicate to recreating your Sailthru templates using Klaviyo’s template builder, it is possible to export your email templates from Sailthru and import them into Klaviyo.

This process involves editing and updating the raw HTML of the email template. If you would instead like to use Klaviyo’s drag-and-drop editor to recreate your templates, check out our guide to learn the ropes of using Klaviyo’s template editor.

Export Your Entire Template HTML from Sailthru

To find the code for your Sailthru templates, click on the template and then click the Code tab. Here, you will have access to the HTML of a given template.


You can copy the template code in its entirety and save it as an HTML file.

Remember to swap out any Sailthru-specific tags with the applicable Klaviyo tags (e.g., first name tags, the unsubscribe link, etc.).

To upload your file to Klaviyo, in your Klaviyo account, navigate to the Email Templates tab and select Create Template. Then, select Import your Template. Here, you will be prompted to select the HTML file from your computer and you can upload the file you just saved.


You can see a preview of what your email template will look like in the Preview tab. Please note that going forward, you will have to directly edit the HTML in order to change the template.

Copy Sailthru Template HTML in Batches

Alternatively, you can export chunks of code from your Sailthru templates, and then import them into text blocks in Klaviyo's drag-and-drop editor. To do this, in your Sailthru account, find the code of a particular template in the Code tab.

Next, in Klaviyo, create a new drag-and-drop template by going to the Email Templates tab and clicking Create Template. Then, select Basic. Here, you can choose an unstyled template as a starting point that you will overwrite with the code from your Sailthru template.


Click the text block in the template, then click Source.


Replace the existing text with the HTML from your Sailthru template, and repeat this process for the parts of the code you would like to migrate directly to Klaviyo. You can then fill in any blanks using Klaviyo's drag-and-drop editor. 

Remember to swap out any Sailthru-specific tags with the applicable Klaviyo tags (e.g., first name tags, the unsubscribe link, etc.).

Set Flows Live

Setting flows live is a key step in ensure that you properly warm your sending infrastructure. Flows are action-based automations that allow you to trigger messages based on customers' activity on your storefront. Because of this, emails sent through flows typically have much higher engagement rates than campaign emails, which are sent in bulk.

To start, turn the following flows live:

Upload Your Engaged Contacts From Sailthru

In Sailthru, isolate your engaged contacts. Your engaged contacts are defined as those who have opened or clicked an email in the last 90 days. Build a Smart List in Sailthru with this criteria. Next, export this audience as a CSV. It is critical that you include the last open, last click, and email address fields. Your CSV should be formatted as follows:


The last open and last click data must be formatted in one of Klaviyo accepted timestamp formats:







If you don't use this format, Klaviyo will not recognize the value as a timestamp. If you're using Excel, you can remove autoformatting by changing the cell format to "Text." If there's no time of day associated with a date, you can set it to midnight by using the HH:MM:SS value 00:00:00.

Next, upload this CSV to Klaviyo and map the applicable fields. In Klaviyo click the Lists & Segments tab, then select Create List/Segment. 


Then, select Upload Contacts. Select your CSV file from your computer or drag and drop it into the upload box.


The import review screen allows you to map the columns in your uploaded CSV to Klaviyo fields. The Klaviyo fields represent where your data is stored on your contacts in your Klaviyo account. The last click and last open timestamps will be uploaded as custom properties, meaning you can select the field you'd like to map them to, along with the datatype. You can add a new custom property by typing the new property name and selecting Create option.


Change the datatype to "Date" to ensure that open and click data is accurately recorded.

Set Up a Dedicated Sending Domain

Setting up a dedicated sending domain allows you to have better control over your email deliverability and is a critical step to ensure that you start off on the right foot when sending with Klaviyo. To do this, follow our instructions on setting up a dedicated sending domain.

Create and Send to a 30-Day Engaged Subscriber Segment

In Klaviyo, build a segment of your 30-day engaged subscribers. Navigate to the Lists & Segments tab and select Create List/Segment > Segment. Build a segment with the following criteria:


Take note of how many people are in your 30-day engaged segment.

  • If there are between 0-50,000 people in your segment, you can send immediately and don't need to use batch sending.
  • If there are between 50,000-100,000 people in your segment, use batch sending and select the option to deliver to 20% over the course of 5 hours.
  • If there are 100,000+ people in your segment, use batch sending and select the option to deliver to 10% over the course of 10 hours.

Next, navigate to the Campaigns tab and select Create Campaign. Select your 30-day engaged segment as the target audience.


Fill in the content of this campaign using one of the templates you migrated over from Sailthru, or create a new one from scratch.

When you are finished editing the content of the campaign, select Review & Send Campaign. Review the campaign settings to ensure that everything is correct. Then, click Schedule or Send. Click Schedule and select your desired send time.

If you need to use batch sending, from the scheduling dropdown, select Send gradually over several hours and then select the appropriate strategy for the number of people in your 30-day engaged segment as outlined above.


Monitor Performance

After sending your first campaign, it's incredibly important to monitor the performance to ensure strong deliverability thresholds. Refer to the table below to benchmark your performance.

  Unique Open Rate Unique Click Rate Bounce Rate Unsubscribe Rate Spam Rate
Great 20% or more 4% or more Less than 0.5% Less than 0.3% 0.0%
Proficient 15-19% 2-3.9%   0.5-0.9% 0.3-0.5%  0.0% 
Room for Improvement 10-14% 1-1.9% 1-1.9% 0.6-0.9% 0.1%
Critical Less than 10% Less than 1% 2% or more 1% or more 0.2% or more

If your performance falls into either the "great" or "proficient" thresholds, you may proceed to sending to a broader subset of customers. Otherwise, continue sending to your 30-day engaged segment until your performance is proficient or great.

Create and Send to a 90-Day Engaged Subscriber Segment

To create a broader segment of engaged subscribers, navigate to your Lists & Segments tab and select Create List/Segment > Segment. Your segment should have the following conditions.


Next, create and schedule your campaigns to send to this group as outlined above for the 30-day engaged segment. 

Be sure to closely monitor your deliverability to ensure that your performance remains strong, and if you have any questions or concerns, please reach out to Klaviyo Support.

Next Steps

After you have quickly ramped up your Klaviyo account, follow the general email service provider (ESP) migration guidelines to ensure that you properly sunset your Sailthru account and migrate the remainder of your data after the BFCM weekend.

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