Is There A Best Time To Send Marketing Emails?

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Imagine this: You’ve crafted the perfect email with a compelling subject line, engaging content, and a clear call-to-action. You hit send, but your open rates and click-through rates fall short of expectations. What went wrong? The answer might lie in your email timing.

Marketers have long debated the “best time” to send emails, but the truth is there’s no universal answer. In fact, 50% of marketers agree that there’s no single perfect time for email campaigns because every business and every individual is different. 

This is why personalization is essential. While 58% of email users check their inbox first thing in the morning, every customer has their own unique rhythm. By understanding these unique behaviors, marketers can deliver messages at the moment they’re most likely to resonate. 

Email send times remain highly relevant but work schedules, time zones, and personal habits all influence when someone is most likely to engage.

How to personalize email send times for each recipient

The key is delivering emails to each of your customers at their own “best time”. However, personalizing send times for every recipient does not scale. 

Marketers face the daunting task of catering to a vast spectrum of customer behaviors and preferences; from early morning commuters checking their inbox on the go to the night owls browsing at home in the late hours. This makes it nearly impossible to manually determine the best send time for each person. 

These complexities multiply when you factor in:

  • Industry variations: What works for e-commerce might fall flat in B2B.
  • Geographical differences: Global audiences span multiple time zones.
  • Changing habits: Customer behaviors evolve, requiring constant adaptation.
  • Resource constraints: Manual personalization at scale is time-consuming and often impractical.

This is where innovations like Send Time Optimization (STO) come into play.

What is Send Time Optimization?

Send Time Optimization (STO) is an email marketing tactic that leverages AI and machine learning to determine the best times to send emails to individual subscribers. For marketers, STO is transformative as it takes the guesswork out of email timing.

How does STO work?

  1. Behavioral Analysis: STO tools analyze each recipient’s location and past behavior, including when they typically open emails and engage with content.
  2. Predictive Modeling: Using this data, the system predicts the optimal time to land in each individual’s inbox.
  3. Automated Delivery: Once the ideal times are determined, your emails are automatically scheduled for delivery at personalized times for each recipient.
  4. Continuous Learning: The system keeps learning and adjusting based on ongoing engagement data, ensuring your timing stays perfect even as habits change.

Best Practices for STO Implementation

  1. Collect Sufficient Data: Ensure you have enough historical data for each recipient to make accurate predictions.
  2. Set Appropriate Time Windows: Allow for flexible delivery windows, typically 12 hours to 7 days, to accommodate various recipient behaviors.
  3. Segment Your Audience: Different audience segments may have distinct optimal send times. Consider segmenting based on demographics, behavior, or engagement levels.
  4. Monitor and Adjust: Regularly review the performance of your STO campaigns and make adjustments as needed.
  5. Combine with Content Optimization: Remember that timing is just one factor. Ensure your email content is relevant and engaging to maximize the benefits of optimal send times.

By leveraging Send Time Optimization and focusing on personalized delivery times, marketers can significantly improve the effectiveness of their email campaigns, ensuring that each recipient receives messages when they’re most likely to engage.

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How Can Send Time Optimization Help You Understand Your Audience?

Send Time Optimization (STO) can also help marketers gain a more comprehensive and nuanced understanding of their audience, leading to more effective and personalized email marketing strategies.

Personalization Opportunities:

STO analyzes individual recipient behavior which can offer insights into their daily routines and habits. This goes beyond basic “best time” assumptions, exposing how your audience allocates attention throughout their day.


These behavioral fingerprints show:  

  • Peak activity windows (e.g. 8 AM commuter check-ins vs. 9 PM leisure browsing)  
  • Device preferences tied to specific times (mobile vs desktop usage trends)  
  • Response cadences that indicate optimal follow-up timing 

By determining individual preferences for email engagement, STO provides a foundation for deeper omnichannel personalization strategies e.g. refine SMS and app notification strategies to match optimal engagement windows.  

Demographic Trends:

By tracking engagement across different segments, STO helps identify how factors like age, location, and job title influence engagement. These insights enable hyper-targeted segmentation strategies that respect audience diversity.

For example:  

  • Global teams might show clustered engagement around regional lunch hours  
  • Working professionals often engage during commute times vs weekends  
  • High-value customers may exhibit unique browsing habits worth replicating  

Evolving With Your Audience

STO systems continuously update their models based on ongoing engagement data. This constant refinement ensures strategies stay relevant even as customer habits evolve.

STO’s machine learning models can detect subtle shifts in behavior, alerting marketers to:  

  • Seasonal pattern changes (holiday shopping vs back-to-work rhythms)  
  • Emerging preferences among generational cohorts  
  • Gradual engagement migrations across platforms or devices  

Leveraging send time optimization as a diagnostic tool rather than just a delivery tactic, gives marketers a multidimensional view of their audience. These insights create a blueprint for customer-centric engagement across every channel.  

Real-World Success Stories: Puma Europe Increase Email Open Rates by 5-10%

Puma Europe, a prominent sports and lifestyle brand, faced a common challenge in global retail: effectively engaging a diverse audience base. 

Their solution? A strategic shift from batch-and-blast emails to intelligent email and send time personalization powered by Emarsys STO.

Blueprint for Timing-Driven Engagement

Puma’s success demonstrates three critical implementation principles (who, what and when):

  • Who: Segment audiences based on their preferences and behaviors.
  • What: Demonstrate customer understanding with personalized content that builds brand affinity. 
  • When: Let send time optimization deliver emails at optimal times and refine as seasonal patterns and shopping habits evolve
We've seen some great results using the Send Time Optimization feature within Emarsys… We can speak to everybody from the people buying on their commute to work through to the late-night shoppers who are shopping in the middle of the night.
David Witts
Senior Manager, Global CRM

Results: 

Puma saw a 5-10% improvement in their email open rates, demonstrating the effectiveness of personalized timing in driving engagement.

As Puma’s results show, when you respect customers’ time, they reward you with their attention.

Embrace the Future: Timing is Personal, Not Universal

Today’s email marketing success hinges on understanding that timing, like your customers, is unique. As the industry evolves, there is an ever-growing emphasis on personalization, automation, and real-time optimization. 

Brands embracing hyper-personalization powered by real-time data and machine learning will forge deeper connections with their audience, turning each send into an opportunity for meaningful engagement.

Remember, your customers don’t operate on a fixed schedule—and neither should your email strategy. The question isn’t whether there’s a universal best time to send emails. It’s how well you can tailor your timing to each unique customer journey. Are you ready to transform your email strategy from guesswork to precision?

Find out more about send time optimization