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Everything You Ever Wanted To Know About Einstein Send Time Optimization For SFMC Journey Builder

Everything You Ever Wanted To Know About Einstein Send Time Optimization For SFMC Journey Builder

Einstein: the very name conjures images of a wild-haired Professor type of person who spouts arcane, potentially world-changing theories about light, ...

Einstein: the very name conjures images of a wild-haired Professor type of person who spouts arcane, potentially world-changing theories about light, gravity and relativity.

But this article is not about Einstein the (real) scientist, but about Einstein the (real) feature in Salesforce Marketing Cloud (SFMC). Specifically, it is about Einstein Send Time Optimization, one of the most exciting new additions to SFMC Journey Builder.

To ensure the success of an email marketing campaign, every email marketer must know that there is no one best time or day to send emails to everyone. Why? Because every subscriber engages with a brand’s emails at different times or on different days. That’s why, marketers need to find the best (or most optimal) time for each subscriber. Only then can they increase their email eyeballs. But doing this manually is impossible. Here’s where Einstein Send Time Optimization can be a true game-changer for email marketers.

So if you are an email developer or email marketer looking for a powerful way to predict the best send times for your subscriber base, then this article is for you.

What is Einstein Send Time Optimization?

In simplest terms, Einstein Send Time Optimization (STO) in SFMC Journey Builder is a way to automatically determine the best (i.e. optimal) time to send an email to a subscriber. This automation, which is powered by Machine Learning, enables email marketing managers to predict when each contact in the journey is most likely to engage with an email within the next 24 hours. By evaluating a number of different factors and criteria, plus each contact’s latest weekly engagement data (‘individualized analysis’), the Einstein STO Journey Builder activity helps marketers and email developers increase email and push notification engagement.

One of the keys to Einstein STO’s prediction success is modeling. Based on its powerful data analysis capabilities, Einstein STO recreates a sending model for sends with the Commercial send classification to predict optimal send times, so that the message is most likely to be opened.

Einstein STO is available with SFMC Corporate, Enterprise or Pro editions with the Journey Builder add-on. To access Einstein STO (if it is available in your SFMC license), click on the Einstein Tab in the Navigation bar.

The Einstein STO Journey Builder activity is available in Flow Controls in the SFMC customer Journey Builder.  Drag and drop the ‘Einstein STO’ activity immediately before any Email Activity in the journey flow. For multiple emails in a customer journey builder flow, drag and drop the ‘Einstein STO’ activity before each email activity.

How does Einstein Send Time Optimization work?

Einstein STO uses 90 days of email engagement data (history) within the Enterprise (top-level tenant in SFMC Email Studio) to determine the best time within the next 24 hours to email each contact. It gathers data for about 20 factors such as:

  • Engagement Behavior: Sends, clicks, opens, unsubscribes, spam complaints and associated timestamps


  • Data and metadata about customer sending patterns and how campaigns are executed

Next, it uses Machine Learning to assign a weight to each factor according to that factor’s ‘influence’ on predicting future engagement behavior.

Then, it analyzes this data and for each contact, assigns a ‘likelihood’ score to each of the 168 hours (24 x 7) in a week to create a sending model. Since customer sending patterns vary greatly, Einstein STO makes use of ‘parameter sets’ that are best suited for different patterns. Then a parameter selector bases its decision on the variation of the sending and opening patterns over 90 days of history.

Each customer’s model is trained only using that customer’s data. Einstein STO uses this data to recommend the optimal email send times that are most likely to lead to opens.

Example: How Einstein Send Time Optimization optimizes the send time of each message in each contact’s journey

Einstein Send Time Optimization Example

Einstein STO sends always occur at the beginning of the best scoring hour for each customer.

The Einstein Send Time Optimization dashboard displays analytics that predict future message engagement. We will cover the dashboard in a subsequent section.

Journey Builder test for Einstein Send Time Optimization

By incorporating Einstein STO into customer journey builder sends, email marketers can improve their chances of delivering each message to each subscriber at the time that’s just right for that subscriber. However, a Journey Builder test for Einstein STO can help them measure the impact of STO and iron out any challenges.

Here’s a step-by-step way to carry out the Journey Builder test for Einstein STO:

Step 1: Select a journey and segment off of a percentage of the traffic using a random split.

Example: the split directs half the contacts in the journey to a path where a wait activity precedes an email activity, and the other half to a branch where the Einstein STO activity precedes an email activity.

Step 2: Drop in the Send Time Optimization tile only on that small branch.

Step 3: After enough contacts have flowed through the Journey Builder test, compare the open and click rates of the email that follows the STO activity with the open and click rates of the email that does. The numbers will give you a true measure of the impact of send time optimization.

How to activate Einstein Send Time Optimization in SFMC for subscribers with low data

What if Einstein Send Time Optimization doesn’t have enough data to create a sending model with optimized send times for each subscriber?

If Einstein doesn’t have enough data to create a sending model for a particular contact, the contact receives messages according to a ‘generalized’ model. This model is derived from sending data already available in Enterprise. To activate it in such cases, follow these steps:

Step 1: In SFMC, expand Einstein, and click Send Time Optimization.

Step 2: Choose a message channel by clicking a tab.

Step 3: Click Activate.

Step 4: Select the send time that the Einstein STO activity uses when enough information about a subscriber is not available to determine the optimal send time.

Step 5: Click Update.

Step 6: Click Settings.

Step 7: Select the time zone that STO observes when sending.

After activation, make sure you allow up to 72 hours to complete the data transfer and analysis required to optimize sends through SFMC’s customer Journey Builder.

This method is not as accurate or personalized as a contact-specific sending model, but compared to not using Einstein STO at all, it still increases the likelihood of opens. That’s why it should still be a crucial element of your email marketing and customer journey builder strategy. 

Einstein Send Time Optimization Dashboard

With the Einstein STO dashboard, a salesforce marketing cloud specialist can easily visualize optimal predicted send times by the day or hour for all contacts in their business unit. Knowing this can help him choose the best time for batch sends.

Here are some of the data types that marketers can view on Einstein STO dashboard:

  • Total email addresses analyzed: The total number of contacts in the business unit or unique email addresses in the tenant
  • Assigned Personalized Send Time: How many contacts or email addresses Einstein STO can suggest a send time for
  • Pending Personalized Send Time: How many contacts Einstein needs more data to suggest a send time for
  • When Are Messages Likely To Be Opened section: Delivery times during the week when contacts are most likely to open email messages
  • When Would Einstein Send section:
  • Total number or contacts or email addresses in the business unit or Enterprise account
  • Optimal send times by hour for a day or for all days of the week

Wrap up

Despite its powerful Machine Learning-based capabilities, not a lot of email marketers use Einstein Send Time Optimization for their email campaigns. Therefore those who do use it automatically get an edge over their competitors. With the capacity to garner more opens and Einstein engagements scoring, Einstein STO should definitely be a part of your email marketing toolkit.

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    Kevin George

    Kevin is the Head of Marketing at Email Uplers, one of the fastest-growing full-service email marketing companies. He is an email enthusiast at heart and loves to pen down email marketing content. You can reach him at or connect with him on LinkedIn.



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