Understanding SMS and MMS quiet hours in flows

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Learn about Klaviyo quiet hours for SMS and MMS flows.

By default, Klaviyo applies quiet hours using the recipient’s phone number area code for US and Canadian numbers. This prevents mobile messages from sending during restricted periods (such as 9 p.m.–8 a.m.) based on area code. When phone number area code is enabled, Klaviyo can also enforce state-level rules in the US.

For recipients outside the US and Canada, quiet hours are based on the eastern time zone in their country (for example, Australian Eastern Time in Australia, Greenwich Mean Time in the UK and Ireland).

Important: Even when the Phone number area code setting is selected, all international recipients are evaluated using their country’s eastern time zone—not their specific region or local time zone.

Quiet hours allow you to avoid sending your text messages during non-preferred hours of the day to your subscribers. This way, you can send SMS or MMS messages during reasonable hours of the day (not when they are sleeping or at other inconvenient times).

This also allows you to more easily comply with telemarketing laws and regulations.

Understanding the importance of SMS and MMS quiet hours

Since text messages are typically viewed as more intrusive, it’s important to send them at legally compliant times. 

Some countries (such as the US and UK) limit the hours when you can send text messages

In general, send in your recipient’s local time and avoid sending:

• Before 8 a.m.
• After 9 p.m. 

* For the US, most of the country is covered by the TCPA, which allows sending from 8 a.m. to 9 p.m. However, several states (such as Florida) have enacted mini-TCPAs for their state and limit sending to between 8 a.m. and 8 p.m. 

** Quiet hours in France are enforced by wireless carriers. This means that you may legally be allowed to send Sundays, but your messages won’t be delivered. The carriers may also decide to filter your other messages if you continue to send outside of the quiet hours. 

When you’re planning to send an SMS message, consider the experience of the recipient. For example, sending a confirmation message immediately after a customer makes a purchase, or replying instantly to a text inquiry provides a great customer experience. 

Quiet hours in Klaviyo

Depending on your location, there are 2 options for quiet hours in Klaviyo: 

• Use Phone number area code (default)
  This bases quiet hours on the recipient’s phone number area code for US and Canadian numbers. You can also enable state-level quiet hours (US only) to automatically follow state-specific rules. For recipients outside the US and Canada, Klaviyo instead uses the  eastern time zone in their country.
• Use eastern timezone 
  This bases quiet hours for a country on its eastern time zone (for example, Eastern Time in the US and Canada, Australian Eastern Time in Australia, Greenwich Mean Time in the UK and Ireland). Brands often use this option with extended hours (like 8 p.m.–11 a.m.) for the most conservative compliance approach.

Note: Klaviyo quiet hours only applies for SMS and MMS flows, not campaigns

Transactional messages

By default, messages marked as transactional do not have quiet hours enabled. If you want to use quiet hours, you can enable this setting for any transactional message. 

For France, quiet hours do not apply to transactional messages or the first message in an SMS welcome flow; however, this only applies if your flow uses the Subscribed to SMS Marketing metric as a trigger.  

Keyword auto-replies 

Quiet hours do not apply to messages that involve Klaviyo default keyword auto-replies (e.g., the message that is sent automatically when someone texts Yes, Stop, Help, etc.). 

For any custom subscribe keyword, quiet hours do apply.

Smart Sending

Quiet hours differ from Smart Sending, but your quiet hours settings might affect Smart Sending. 

Both quiet hours and Smart Sending are checked at send time, not the time you scheduled the message. However, quiet hours are checked before Smart Sending. 

For example, say someone just received a text message. Then, they get triggered for another SMS during quiet hours. In this case, Klaviyo:

1. Checks that the message falls during quiet hours. 
2. Delays the message until quiet hours are over. 
3. Once quiet hours are over, checks the Smart Sending window. 
   • If enough time has passed (i.e., the message falls outside the Smart Sending window), Klaviyo sends the message. 
   • If not enough time has passed, Klaviyo skips the message.

Daylight savings hours changes

Daylight savings time (DST) applies for each respective region and country as it occurs. 

For example, if you are sending to recipients in the US, starting the second Sunday in March at 2 a.m., Klaviyo automatically switches to EDT, and starting the first Sunday of November will switch to using EST. Thus, Klaviyo will match the correct local time in accordance with daylight savings time.

You can see these changes in your SMS settings as they update.

Enable or disable quiet hours for a flow message

To turn off quiet hours for a particular SMS or MMS:

1. Click on the SMS message in the flow.
2. In the details panel, scroll down to the Settings section.
3. Click the checkbox next to Enable SMS quiet hours.
   
4. Click Save at the bottom of the details panel.
   • You can always change your global SMS quiet hours settings by clicking SMS settings. 

Quiet hours are checked at message send time. For example, say you have quiet hours enabled so messages can only send between 11 a.m. and 8 p.m. If at 7:05 p.m., you change the quiet hours to start at 7 p.m., any messages that were about to go out will now wait until 11 a.m. the next morning.

What happens when a recipient cannot be sent to yet

When quiet hours is enabled and the flow is live, any message scheduled to go out during quiet hours will wait to send. 

Recipients go into the Waiting queue and their message will wait to send until the next available sending time. While in this queue, recipients pause their journey in the flow (i.e., they don’t move past the SMS to any following splits, time delays, emails, etc.). 

Once quiet hours are over, the flow sends the SMS or MMS to the recipient, removes them from the Waiting queue, and allows them to continue in the flow.

View recipients waiting due to quiet hours

In the left-hand sidebar for a flow message, you will see an Analytics (Last 30 Days) section. The line for Waiting activity will display how many recipients are waiting to receive this message.

If you click on this line, it will take you to the message’s Recipient Activity tab with the Waiting section automatically open. This section will show the number of people waiting to receive the message during their preferable hours that do not fall during quiet hours.

Additional resources

• Help Center: 
  • How to change your quiet hours settings
  • Basics of SMS compliance 
  • Understanding Smart Sending in Klaviyo
• Blog post: SMS marketing strategies for all levels [+12 Pro tips]