---
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title: Einstein Send Time Optimization for Journey Builder
collection: admin
version: current
locale: en-us
portal_url: https://docs.salesforce.com/admin/current/en-us/mktg/264-0-0/mc_jb_einstein_sto.md
canonical_url: https://help.salesforce.com/s/articleView?id=mktg.mc_jb_einstein_sto.htm&release=264.0.0&type=5
source_site: help.salesforce.com
content_type: documentation
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description: Einstein Send Time Optimization (STO) uses machine learning and 90 days of email or push notification engagement data to determine the best time within the next 24 hours to send a message to each contact. Include the Einstein STO activity in a journey immediately before an email or push notification activity to reach contacts when they’re most likely to engage. Or preview Einstein’s optimal send times for a data extension before you send. To use this activity, activate Einstein Send Time Optimization for your business unit.
products:
  - Marketing
  - Marketing Cloud Engagement
release: "264"
---
# Einstein Send Time Optimization for Journey Builder

Einstein Send Time Optimization (STO) uses machine learning and 90 days of email or push notification engagement data to determine the best time within the next 24 hours to send a message to each contact. Include the Einstein STO activity in a journey immediately before an email or push notification activity to reach contacts when they’re most likely to engage. Or preview Einstein’s optimal send times for a data extension before you send. To use this activity, activate Einstein Send Time Optimization for your business unit.

### Required Editions

<table class="slds-table slds-table_bordered slds-max-medium-table_stacked slds-m-bottom_small edition"><colgroup><col></colgroup><tbody><tr class=""><td class="slds-cell-wrap" style="vertical-align:top;">Available to customers with Marketing Cloud Engagement Einstein terms for <strong class="uicontrol">Corporate</strong>, <strong class="uicontrol">Enterprise</strong>, or <strong class="uicontrol">Pro-edition</strong> accounts with the Journey Builder add-on.</td></tr></tbody></table>

Einstein Send Time Optimization helps marketers increase engagement with email or mobile messages. The Einstein STO Journey Builder activity can send email or push notifications to each contact at the time when that contact is most likely to engage with the message.

## How Send Time Optimization Works

Einstein gathers data for approximately 20 factors. Factors include engagement metrics such as the number of messages sent to and opened by a contact and the day of the week the message is opened. Then, using machine learning, Einstein assigns a weight to each factor according to that factor’s influence on predicting future engagement behavior. Einstein analyzes this data and assigns a likelihood score to each of the 168 hours in a week for each contact. Send Time Optimization uses this information to recommend the send times that lead to increased engagement.

With Einstein Send Time Optimization you can preview the best send times for a data extension that you plan to use for sending. Einstein analyzes a sample of the total number of contacts to identify the best send times for those contacts. To preview send times for a data extension navigate to the Einstein Overview.

#### See Also

- [Activate Einstein Send Time Optimization](https://help.salesforce.com/s/articleView?id=mktg.mc_jb_activate_einstein_sto.htm&language=en_US)
- [Einstein Send Time Optimization Dashboard](https://help.salesforce.com/s/articleView?id=mktg.mc_anb_einstein_sto_dashboard.htm&language=en_US)