Once Send Time Optimization (STO) is enabled for your account, it will appear on the Scheduling page of the eligible email campaigns, and in the Send email node of Automation Center programs.
You turn STO on and off via the toggle switch, and can use it for campaigns launched immediately or those scheduled for a later date.
As Send Time Optimization needs past contact behavior data to determine the optimal sending times, we do not recommend using STO until you have at least 1 month of email campaign history. If you turn STO on too early, it will distribute contacts randomly among the child launches and this can actually result in a decline in responses.
Please note that you can only enable STO in a program if its state is In design. You cannot turn STO on or off once the program's state has been changed from In design to another one.
To enable or disable STO in an active program, you have to pause or end it, then copy it to create a new program. Now you can turn STO on or off in the new program.
Once you feel you have launched enough email campaigns, you should start to use STO for all your batch campaigns. It will take a number of campaigns before STO has learned enough about the response habits of your customers. Until then, response rates will vary and may even appear to decline. You will be notified on the Send Time Optimization Dashboard widget when the model has become stable enough for the reporting to be statistically relevant.
For more information, read the Send Time Optimization - FAQ.
Currently, STO does not support campaigns that use relational segments and personalization with relational data at the same time. In such cases, do not enable STO as contacts may be excluded from the launches.
Launching an email campaign with STO
When your email campaign is ready to launch, activate Send Time Optimization on the default Scheduling or Advanced Scheduling page. You then have two options:
- Launch now - Emarsys will immediately create a control group comprising 10% of the launch list, and then calculate the optimal sending times for the remaining contacts. Once the calculations are finished, the campaign will be launched to the control group and the first STO launch will take place on the next even or odd hours, depending on your time zone. The remaining contacts will be divided into 11 further launches every two hours.
- Launch control group at - Emarsys will launch the campaign to the control group at the specified time. The 12 STO launches will start and be spread evenly on the calendar day selected for the launch. The time zone of the calendar date is defined on the campaign's Scheduling page.
This feature can currently only be enabled for batch email campaigns.
- By launching now, the first STO launch is scheduled for even hours in UTC time, which is then converted to your time zone. Depending on your UTC offset, the launch can happen on even and odd hours as well.
- If a daylight saving time change alters the time zone difference between your local time and UTC time, your local launch times will shift accordingly.
- If you activated the BCC option in the Email Settings step, only the first STO launch will be BCC'd to the email addresses you selected.
You can see how the Launch now and Launch control group at options work in the following image:
Advanced vs simple scheduling
There are some differences in behavior for STO depending on whether you are using simple or advanced scheduling.
When using Advanced Scheduling:
- If you are using A/B testing, STO will only be enabled for the final mailing. All the versions you use to test will be launched as normal emails.
If you are A/B testing a campaign with STO, then you need to launch the test for version A and B as well. After testing both versions, STO will use the one that produced the best results.
- It is not currently possible to abort the STO launches. You can, however, unschedule a scheduled launch when there are at least 30 minutes left until the launch. If it is still critical to abort the STO launch, contact Emarsys Support to abort your emails.
- The launches are started on the scheduled day at the time defined in the launch schedule. If you want to ensure that the launches are all sent on the same calendar day, you must set a launch schedule time of 00:00.
Using STO in the Automation Center
You can also enable STO for batch email nodes in any program that does not start with a transactional entry node (i.e. not Form, Data Change or New Contact).
The behavior is the same as for batch emails:
- A 10% control group is automatically created and launched as soon as the email is triggered.
- The remaining 90% of contacts will be split up in 12 launches over the following 24 hours.
- The responses will show up on the STO widget.
Additionally, the following behavior should be noted:
- Pausing or aborting a program will not stop STO emails that are already scheduled for launch. If it is still critical to abort the STO launch, contact Emarsys Support to abort your emails.
- Launches smaller than 100 contacts will not be counted on the STO widget (as there will be no control group).
- When an AC program sends out a campaign using STO, the next node will only be processed when all mail has been sent out, which means that an STO node will always take 24 hours to process.
- Currently, STO does not support campaigns that use relational segments and personalization with relational data at the same time. In such cases, do not enable STO in the Send email nodes as contacts may be excluded from the launches.
- Additionally, STO campaigns distributed with Automation Center programs appear to be sent out in two batches instead of twelve in the Email Analysis tab. However, the AC program itself will register the correct twelve launches. The total number of sent emails should be the sum of the two displayed batches.
STO needs to calculate the launch time for every contact in your launch list. When sending your first campaign, you should allow at least two hours for the initial calculations.
For subsequent campaigns, the time it takes for STO to calculate the best sending times may range from a few minutes to two hours. The actual calculation time depends on the size of your database as well as the complexity of the contact segment and the launch list.
Monitoring the performance of STO campaigns
On the Dashboard
The Send Time Optimization widget on the account Dashboard compares the response rates of STO campaigns against those of their control groups.