Send Time Optimization: Email delivery timed to perfection
Written by
Tejas Pitkar
Tejas Pitkar

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Send Time Optimization: Email delivery timed to perfection

Published : September 15, 2021 | Updated : May 06, 2024

This is part 1 of a 2-part series about Netcore’s latest Send Time Optimization algorithm. This part explores why perfecting email send times can help marketers like you in improving the email program performance.

Recently I met an email marketer friend working for a popular e-commerce website. He looked stressed and on further querying, told me he had been losing his sleep over his job.

“Running an email program for e-commerce is like driving a motorsport car. There are so many controls, gear shifts, buttons, and communication loops that a racing driver has to go through daily,” said my friend.

Well, rightly said.  There are a lot of decisions that need to be made on a typical workday – important ones that could affect his company’s bottom line.

“There are email metrics to monitor, campaigns to optimize for every opportunity for business growth. There are a lot of choices I have to make daily.”, he added.  

Email marketers often get caught in the loop of customer experience decisions like How much of the email list should be engaged?
Should the email campaign be sent in the morning or afternoon? 

Are the open rates up to industry benchmarks or do they need improvement? 
Multiply these by 365 days a year and you can imagine how many questions they need to find answers to!

If you use Netcore Cloud’s Customer Engagement Platform, the range of customer experiences you can create from emails, personalization, AI-powered automation, app, and web push are limitless.

In today’s fast-paced marketing scenario, growth-focused marketers need to have parts of their email program automated. Like sitting behind the wheel of a self-driving car in auto-drive mode.

That’s why Netcore keeps developing smart marketing capabilities to automate your email programs. This automation takes the guesswork out of your daily tasks and make them…well… ‘routine’.
One such feature that our product team developed is “Send Time Optimization (STO)”
This post provides insight on what STO is and how it can help marketers in automating their email delivery and gain astonishing results.

What is Send Time Optimization?

Send time optimization (STO) is an AI-powered capability for your email marketing campaigns. It closely examines past email interactions and customer engagement, and determines the accurate time to send the message when they are most likely to open their mailbox.

And it can be scaled to accurately deliver emails for millions of customers at the right time.

Sounds exciting? Read on…

How does Send Time Optimization matter for email marketers?

Two questions that may come to your mind:

How will STO impact email performance?

– How will it benefit my customers?

Personalization has acquired a whole new meaning for marketers in 2021. It goes not only beyond crafting individualized content but also sending it at the right time to each customer. This is where STO comes into play.

Integration of such AI-powered technologies, and customer engagement solutions with email programs and automated journeys has revolutionized how companies interact with consumers.

But why does it warrant use in today’s email marketing ecosystem?

In delivering emails at accurate times, STO can help you:

1. Make your emails stand out

According to Statista, the number of email users worldwide stands at 4.26 billion in 2022. This number is expected to increase to over 4.73 billion by 2026.

That’s how flooded your customers’ inboxes have become!

To stand out from your competitors, you will have to get creative and put your email on top of customer’s inboxes. Get on top of their minds.

STO automates the process of sending emails to each subscriber according to their best time to check emails. Not only that, but it also allows you to scale the timed delivery for millions of subscribers.

2. Engage with customers at an ideal time

With the world still reeling from a pandemic, marketers are showing urgency to retain customers by reaching out to them at the right time. Retention is the new acquisition.

According to a consumer study, 32% of the surveyed consumers are less likely to purchase from a brand if their communications are poorly timed.

The new email checking timings had to be recalibrated during the lockdowns by companies to adapt to new changes. AI-powered STO can easily relearn new behaviors and provide detailed insights for you to adapt to changing consumer culture.

What customers need is not ‘real-time’ but the ‘ideal time’ to engage.

Personalized content attracts readers’ attention and piques their interest to explore more. STO achieves the level of personalization by optimizing your send times according to demographics and regions.

For instance, if you are a global online store (Amazon)  with consumers worldwide, STO considers individual time zones to avoid sending messages at odd times like late nights, early mornings.

STO makes the email delivery personal to the targeted customer.

A message sent at the right time can lead to an ‘aha’ moment for your customers.

3. Achieve better deliverability

It’s a proven fact that Mailbox Service Providers (MSPs) prioritize subscriber engagement as one of the parameters to determine positive customer engagement levels. The MSP spam filter algorithms are merit-based and work specific to the individual sender.

‘Email opens’ tell a better deliverability story than anything else, hence positive customer engagement is important for marketers in their quest to reach the inbox.

A study found that 20% of customers wish to receive emails at their own suitable time. STO helps by putting emails on top of your customer’s inbox every time they check. This activity attracts high opens and clicks.

So, the more you reach at a suitable time, the better your inbox placement.

Higher customer engagement breeds better deliverability which in turn gets rewarded with greater ROI.

Talking about ROI…

4. Improve conversions by adapting to customer behaviors

So far, we know that STO can increase your email visibility and attract customer engagement.
But at the end of the day, nothing makes an email marketer happier than increased conversions.

Improving email conversions is an important KPI for a company selling online products.

What if we tell you that STO can increase your email ROI as well?

An advanced version of STO, powered by machine learning algorithms, adapts the send times to your customers’ purchase behaviors. STO tracks not only when your subscribers read their emails but also specifically when they make purchases.

For instance: Adam checks his emails on the daily commute to work in the morning, but only makes purchases when he’s back home in the evenings.
STO will smartly automate the send time for Adam in the evening for promotional offers and send educational emails in the morning.

STO can thus be tweaked to consider buying behaviors.

How will Apple privacy changes impact STO?

Now you must be wondering will STO be of any use post-September 2021?

Yes, it will still be a valuable tool but will need some tweaking.

With Apple’s MPP changes set to be introduced in September, open tracking pixels could get blocked for Apple devices on iOS15. This announcement has led marketers to fear the worst for technologies that depend heavily on open metrics like STO.

Post the pixel blocking, the open rates might show 100% for all Apple mail users. It means if you recalibrate your STO opens post the privacy changes, you will receive a skewed performance.

So we suggest you should start collecting preferred delivery time details of the entire list right now so that you can be confident using the same when the changes kick in.

Also for new subscribers tweak your STO algorithms to consider clicks, purchase history, website browsing activity history, user drop-offs, etc. to get a better handle on customer engagement times.

Tweak the STO algorithms now for your list to get a better head start on calibrating new send times.

Read more here on how to manage your email program with the upcoming Apple privacy changes.

Dipanjan Bhattacharjee
Product Manager

Dipanjan Bhattacharjee
Product Manager
Netcore Cloud

STO empowers marketers with the ability to send emails at the most optimal time to each customer within their target audience. Netcore’s STO model has seen promising results with high customer engagement as the emails appear at the top of customers’ mailboxes.

With the upcoming Apple privacy changes, STO metrics will need to be tweaked accordingly.
‘Raman’ has the intelligence to adapt to new customer behaviors and engagement patterns. I feel that STO should be a part of every email marketer’s tactics to improve their customer response.”


STO technology helps marketers truly understand their email audience and the time when they are active.

STO helps a marketer to:

  • Stand out in a crowded customer inbox
  • Engage customers at their preferred time
  • Deliver personalized messages at precise moments
  • Improve inbox placement with high customer engagement activity
  • Get more conversions by adapting to customer buying times

In part 2 of this series, we will reveal how our product and data science teams created our latest STO model that benefited global brands with stunning results.

Learn more about Send Time Optimization and book a demo to experience our AI-powered email delivery at its best!


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Written By: Tejas Pitkar
Tejas Pitkar
Tejas Pitkar is a Senior Product Evangelist at Netcore Cloud. He likes analyzing data and diving deep to find valuable insights for marketers. He is credited for writing Industry benchmark reports and marketing leaders’ reports. He also likes to give back to the email industry with his volunteer work at the Only Influencers Diversity Committee. An #emailgeek at heart, he likes writing blogs, sharing email knowledge, and making thought-provoking videos on all things email. He enjoys hiking, backpacking, reading books, and drinking his favorite Chai, in his free time.