Send Time Optimization (STO) is a feature that uses an algorithm to find the best time to send the campaign to the subscribers in the next 24 hours based on their engagement history.
This article explains the following:
Why do we need STO?
STO enables you to adapt your campaigns to the individual usage patterns of your subscribers. Your emails will be more likely to show up at the top of the inbox and more likely to be engaged with.
How does 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 have a weight of 0.4, and clicks have a weight of 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 the score of 3.8 (3x1 + 2x0.4) and will be chosen as an optimal emailing time for Jane Doe.
Her slots are updated whenever Jane opens or clicks an email, and her optimal time is recalculated.
FAQ
Q: What happens if the subscribers do not have past events, such as opens or clicks?
A: The campaign will be sent right away.
Q: When are the time-optimized emails sent?
A: These emails are sent at the beginning of each time slot.
Q: Can STO be used in A/B campaigns?
A: This feature is not supported in A/B campaigns.
Q: Can STO be used in recurring campaigns?
A: Currently, this feature is not available for recurring campaigns.
Q: Does STO count days of the week while calculating the scores?
A: The day of the week is not counted in this calculation.
Q: What happens if two slots have the same score?
A: The previous optimal hour is not updated until a new one has a higher score.
Q: 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?
A: It is not updated. The campaign will be sent regarding her optimal time while her STO campaign is set.
Q: Can STO be used when an automated warm-up is enabled?
A: STO is not supported during the warm-up period.