Guide to Smart Sending in Klaviyo

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Smart Sending allows you to limit the number of emails or text messages someone can receive from you in a given period of time. This is a good way to prevent your subscribers from receiving too many messages at once if you have many active flows and campaigns.

In this guide, you will learn more about Smart Sending; how it works for campaigns and flows; as well as how to edit the timeframe, disable it, or A/B test it. 

About Smart Sending

When an email or SMS message has Smart Sending enabled, Klaviyo will automatically check to see if that recipient has received a message from you within your account's Smart Sending period before it sends. If this person has received another message from you too recently, they will be skipped from receiving the current message.

Your email and SMS message Smart Sending windows are configured separately in your account settings. 

When a message is skipped due to Smart Sending, it will not automatically be rescheduled to send at a later time. This is because most messages are time-sensitive. If you want to resend an email that was skipped due to Smart Sending, you can do so from either an individual’s profile or from navigating to the specific flow message and clicking View all Analytics > Recipient Activity. For more details, check out this guide to resending flow emails.

You can also manually clone campaigns or recreate a flow message as a campaign and then sending the new version. Once a customer enters a flow triggered by a specific event and either gets a message or is skipped (or processed in the flow with a different outcome), the customer cannot be re-queued for the flow.

Currently, it’s not possible to resend a text message to someone who was skipped due to Smart Sending except by doing so manually. 

Change the Smart Sending Timeframe

As mentioned the Smart Sending timeframe for email and SMS are separate, so you can adjust one without affecting the other. 

Updating the smart sending window does not retroactively affect recipients. For instance, if you update the Smart Sending window from 16 to 6 hours, and you sent a campaign 8 hours ago, recipients will still be skipped due to Smart Sending for the next 8 hours for any new campaigns. 

Email Smart Sending Window

By default, the email Smart Sending window is 16 hours. 

  1. Navigate to the account dropdown in the upper right-hand corner of your screen
  2. Select Account
  3. Click Settings
  4. Select Email
  5. Update the number of hours under Smart Sending Period
  6. Check the box to Ignore transactional messages if you send transactional emails
    • In almost all cases, Smart Sending should remain disabled for transactional emails, as these are messages that customers anticipate receiving and search for in their inboxes


SMS Smart Sending Window

By default, the SMS Smart Sending window is 24 hours. 

  1. Navigate to the account dropdown in the upper right-hand corner of your screen
  2. Select Account
  3. Click Settings
  4. Select SMS
  5. Edit your Smart Sending period within the SMS Sending Settings area 


Disable Smart Sending for a Message


Smart Sending is enabled by default for all campaigns. You can choose to disable Smart Sending on a per-campaign basis. We recommend keeping Smart Sending turned on for most, if not all, marketing emails.

In step 1 of the campaign, toggle off the option to: 

  • Email: Skip recently emailed profiles
  • SMS: Skip recently messaged profiles




Smart Sending is not enabled by default for flow messages. You can choose to enable Smart Sending for an individual flow message.

  1. Click on an individual flow message
  2. Click Smart Sending under Settings on the left-hand side
  3. Toggle on Smart Sending



Smart Sending and A/B Testing

A/B tests that receive no results due to Smart Sending are automatically cancelled. This means that everyone in the test pool for your A/B test campaign got skipped because they received another message too recently. If you receive an in-app notification like the one below, your A/B test has been canceled and you need to resend your campaign to reach your recipients. 


Additional Resources

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