Troubleshoot Flow Sending

Last updated at:


If your flow isn't working as expected, follow this article to troubleshoot common issues. 

Is Anyone Being Skipped?

In the left-hand panel for a given flow email, you will see an Analytics (Last 30 Days) section. Here, you will see a line for skipped activity.

If you click on this line, you will be taken to the email's Recipient Activity tab with the Skipped section automatically popped open. Here, you can see why individuals may have been skipped at send time for the flow email.



The Skipped dropdown will show you exactly who has been skipped by the flow and why. There are a variety of possible skipped reasons.

General skipped reasons include:

  • Smart Sending
    Skipped because smart sending is enabled and they received another email too recently.
  • Person No Longer in List
    Skipped because they are no longer in the trigger list or segment.
  • Fails Flow Filters
    Skipped because they don't meet the criteria in the flow filters at send time.
  • Fails Additional Filters
    Skipped because they don't meet the criteria specific to this flow email at send time
  • Person Deleted
    Skipped because the profile no longer existed at send time.
  • Action Deleted
    Skipped because the Email, SMS, or Update Profile Property action no longer existed at send time.

Email-specific skipped reasons include:

  • Missing Email
    Skipped because there is no email address associated with their profile.
  • Person Suppressed
    Skipped because they unsubscribed or hard bounced from all email.
  • Email Syntax Error
    Skipped because the email template contains a syntax error.
  • Catalog Item Unavailable
    Skipped because a product in the rendered email content is currently out of stock or not available.
  • Over Email Limit
    Skipped because you went over your account's sending limit.
  • Unable to Send Email
    Skipped because we ran into an unexpected error at send time.
  • Invalid From Email
    Skipped because the From Email address is not a valid address.
  • Error Retrieving External Data
    Skipped because there was an issue retrieving data from an external source (for example a coupon code from Shopify).
  • Duplicate Email
    Skipped because the same email to the same address was already sent.
  • Coupon Category Unavailable
    Skipped because the email contains a placeholder to pull in a dynamic coupon restricted to a certain category, and the category was deleted.
  • No More Uploaded Coupons Remain
    Skipped because the email contains a placeholder to pull in an uploaded coupon and no more uploaded coupons remain.
  • Coupon Code Doesn't Exist
    Skipped because the coupon code you’re referencing in an email either doesn’t exist or doesn’t match the coupon code you created in your Coupons tab. Coupon code names are case-sensitive.
  • Email Cancelled
    Skipped because the email had been cancelled at or before send time.
  • Suspicious Email
    Email addresses that have hard bounced across the Klaviyo infrastructure.

SMS-specific skipped reasons include:

  • Unable to Send SMS
    Skipped because we ran into an unexpected error at send time.
  • Missing SMS Consent
    When someone triggers a flow and we have their phone number but no SMS consent timestamp, they will be skipped from receiving the SMS message.
  • Missing Phone Number
    Skipped because the recipient does not have a phone number associated with their profile.
  • Phone Number is Not Valid
    Skipped because the recipient does not have a valid phone number.
  • Phone Number is in Country Not Supported by SMS
    Skipped because the recipient's phone number is not a US number. SMS sending is currently only available for US recipients.
  • No Sending Number
    Skipped because there is no sending number associated with your account. You can add a sending number to your account in Account > Settings > SMS.
  • Not Enough Funds Available
    Skipped because you have insufficient funds in your account to send SMS messages. You can add funds in Account > Settings > SMS.

Skipped Due to Smart Sending

A common reason recipients are skipped is Smart Sending. Smart Sending allows you to limit the number of emails someone can receive in a given period of time so you don't have to worry about overwhelming people even if you have a lot of live flows and campaigns.

By default, Smart Sending limits emails to once every 16 hours and SMS messages to once every 24 hours. You can update this setting in your account's settings.

You can see whether Smart Sending is enabled for a given email by viewing the email card — the Smart Sending icon will light up green if this feature is enabled. 

Smart Sending can be toggled on or off from the Settings panel for a given flow email.

Is Anyone Actually Meeting the Flow's Conditions?

If you check out Recipient Activity and see that nobody has been queued up for the flow and nobody has been skipped for any reason, chances are there is something wrong with the flow’s setup. One of two things is true:

  • Nobody is meeting the flow’s conditions, but the flow is configured correctly
  • Nobody is meeting the flow’s conditions because the flow is configured incorrectly

To investigate this, you can look at a few different things.

1. Preview the flow trigger setup
This tool allows you to preview your trigger logic with example recipients to ensure that your flow is set up the way you would like.

2. Consider the flow’s trigger metric and view recent activity
To do this, click on the metric from within the flow’s trigger box. You’ll be taken to either the analytics report for the metric (if it’s an event-triggered flow) or the list or segment used as the trigger (if it’s a list- or segment-triggered flow).

  • If you can see a lot of trigger activity but nobody is actually getting queued up for the flow, it means there is likely something wrong with the flow’s filters.
  • If there is no activity around the flow’s basic trigger, the next step is figuring out why. If the flow is triggered by an event, there is likely an integration issue.

3. Consider the flow's trigger filter and flow filters

If the trigger action itself doesn’t seem to be the problem, and you need to investigate the trigger filters and flow filters, the best thing to do is to create a dynamic segment that matches the flow’s conditions as closely as possible. Using the segment builder, you can test out certain conditions to get a better understanding of who a flow is going to capture. A few common issues here:

  • A series of filter conditions are separated by AND instead of OR (or vice versa) — you can review this guide to better understand the use of AND/OR when stringing together flow filter conditions.
  • The flow filter may actually be keeping everyone out. If you have created a time-relative filter, or a multi-conditional filter, we recommend walking through the logic of how someone would get queued up for your flow. For example, if a flow is triggered by the Placed Order metric, and the first email is scheduled to send after 3 days, adding a flow filter that says has Placed Order zero times in the last 7 days will cause everyone to get skipped by email 1. By default, everyone that is queued up for email 1 will have placed an order in the last 7 days because they were added to the flow based on this action merely 3 days before.
  • The filter conditions are set to the wrong data type — e.g., a list property is being filtered as a string (or vice versa). You can learn more about data types here.

Have You Hit Your Account's Email Send Limit?

If you’re seeing unexpected flow sending behavior, a quick thing to check is whether or not you have hit your email sending limit (either an “all time” limit, or a monthly send limit). A quick check of your account settings will reveal if this could be a contributing factor.

For example, if you are on a free plan, you are limited to 500 emails per month. If you are seeing flow email deliverability drop off at a certain point every month, it might be because you are hitting this 500 email/month limit at some point mid-month causing all sending to stop at this time.

Common Issues

Welcomes Series Isn't Sending to New Subscribers

There are two situations where a new subscriber who is added to a list will not also be queued up for a welcome series (or any flow) configured to trigger off this list:

  1. It isn’t possible to trigger flows off of lists that are synced through other ESPs, like Mailchimp. If you are syncing all of your subscriber lists from Mailchimp, you will not be able to configure flows to send to these subscribers as they opt in.
  2. If someone is added to your newsletter list by clicking the Subscribe to Newsletter box at checkout in your ecommerce store, they will NOT be queued up for your welcome series flow. This is a default setting because typically the welcome series is designed for new customers/visitors. Someone could check this Accepts Marketing box for the first time during their 100th purchase, and it might not be appropriate for this person to receive your welcome series. If you would like us to adjust this setting for your account, please contact our Success Team.

Flow Filter Based on Items or Collections Has the String Data Type

A list is any array of values, e.g., ["Offer1", "Offer2"]. In Klaviyo, the list data type is used when the goal is to collect an array of words/phrases, where each single item in the array can be identified individually.

One common use case for this list data type in Klaviyo is when different tags are being collected as a single property, such as the Shopify Tag property. We store one Shopify Tag property and then as more tags get assigned to a customer, we just add them to the Shopify Tags array, such as: ["Tag1," "Tag2," and "Tag3"]

Another common use case is when Klaviyo captures a Placed Order metric through an integration, and the data we receive along with this Placed Order metric includes an Items property. This Items property captures all items purchased in the order and it is always synced and stored as an array, which is the list data type in Klaviyo. This allows us to store the one property — Items — but have that property include a series of values (e.g., each item purchased in the single order), where each value in the array can be identified individually. The same is true for the Collections property synced along with Placed Order or Ordered Product.

If you are filtering based on Items or Collections and using "equals" where the data type is string, your flow will not work. Instead, the data type must be set to list and the condition will look like, "where [Items or Collections] contains _____."

Flow Sending Delays

During high-volume sending periods flow, emails may see up to a 15-minute delay from the time they are scheduled to send. If you're seeing delays in your flow emails beyond 15 minutes, please contact our Customer Success team.

Additional Resources

Get more details on how to preview the flow trigger setup.

Learn why a profile is queued for a flow multiple times in this article

Find out more about Smart Sending in Klaviyo


Was this article helpful?
82 out of 266 found this helpful