# Overview

For **segment triggered flows**, if you want your flow to send as soon as data refreshes you can choose **send immediately when segment updates** when [creating your flow](🔗).

However, if you want to avoid sending during certain hours, e.g. during the night, you can specify a specific window during which flows will send. You actually accomplish this by specifying the only time you _do_ want messages to send. During this _send window_, any time the data refreshes, your flow will send again during that time period.

For example, if you set a send window to 3-9 PM, any time the flow data refreshes within those 6 hours, your triggered message will send. However, even if the data refreshes at 9:30 PM, the message won't send again until that send window opens up at 3 PM the next day, and only if the receiver is still a member of the segment.

## Data pipes, loads, and send times

This diagram illustrates how data pipes and loads affect send time within a set send window.


Send Window Diagram

6 hour increments

Send windows must be six hours at minimum. For windows less than six hours, use a [**send time**](🔗), which has a two hour send window on its own.

# How to set a send window

Segment triggered flows

Send windows are only available for segment triggered flows

  1. Create a triggered [flow](🔗).

  2. Configure the trigger to _When a contact enters the segment_.


Create a segment triggered flow

  1. Choose your segment and configure options, then scroll down to the next section, **Send Time**.


Send Windows

  1. Under **Send Time**:

    1. Choose **Send immediately when segment updates.**

    2. Expand **Advanced**.

    3. Check **Only send at certain times**.

    4. From the drop downs, choose a **Timezone** the window will be based on, then the associated **Hours** and **Minutes** that include your send window. The window must be at least six hours long.

  2. Complete your [flow](🔗) as usual.