Send Time Optimization (STO) is a feature that utilizes an algorithm to determine the optimal time to send the campaign to subscribers within the next 24 hours, based on their engagement history.
This article explains:
Why do you need STO?
STO enables you to adapt your campaigns to your subscribers' usage patterns. Your emails will be more likely to show up at the top of the inbox and be more likely to be engaged with.
How can you enable STO?
After creating your email campaign, click the Enable Send Time Optimization box in the Launch step, and your email will be sent to customers at the best time.
How does the STO work?
STO logs the engagement metrics of each subscriber for 1-hour slots in a day (which makes 24 slots in total).
Take, for example, Jane Doe as a subscriber.
{
"1": {
"clicks": 1,
"opens": 2
},
"2": {
"clicks": 0,
"opens": 1
},
...
...
...
"24": {
"clicks": 3,
"opens": 2
}
}
The optimality score is calculated for each time slot by giving weight values for opens and clicks. Opens weight 0.4 and clicks weight 1.
The time slot with the highest optimality score is recorded as the “optimal emailing hour” for that subscriber. The example of 00.00 has a score of 3.8 (3x1 + 2x0.4) and will be chosen as an optimal emailing time for Jane Doe.
Whenever Jane opens or clicks an email, her slots are updated, and her optimal time is recalculated.
The campaign status with Sent Time Optimization will be Running until all users receive the email within 24 hours after the campaign is launched. Emails are sent according to the user’s email_at attribute, which is calculated based on clicks and opens of that user.
Deep Insights
What happens if the subscribers have no past events, such as opens or clicks?
The campaign will be sent right away.
When are the time-optimized emails sent?
These emails are sent at the beginning of each time slot.
Can STO be used in A/B campaigns?
This feature is not supported in A/B campaigns.
Can STO be used in recurring campaigns?
Currently, this feature is not available for recurring campaigns.
Does STO count the days of the week while calculating the scores?
The day of the week is not counted in this calculation.
What happens if two slots have the same score?
The previous optimal hour is not updated until a new one has a higher score.
What happens when Jane opens/clicks an email after her emails are set for the STO campaign? Is her optimal time for this campaign updated?
It is not updated. The campaign will be sent regarding her optimal time while her STO campaign is being set.
Can STO be used when an automated warm-up is enabled?
STO is not supported during the warm-up period.