Send a mail merge only during a time range
Learn how to specify a start and end time that your campaigns sends, e.g. for sending only during business hours.
Open advanced options
In the campaign manager select the link titled "Show advanced campaign features" to open the advanced options.
Options: Send between X - X
The campaign will be generated to only send emails between the specified start and end time. Both values must be set and default to the start (00:00) and end (23:59) of the day. The end time cannot be before the start time. See here if you are trying to delay sending to a specific day. Both options can be set together.
Your Outlook does not have to be open for the messages to be sent once the generation has finished.
The delay is unfortunately not visible in Classic Outlook on the Desktop but to verify the scheduled time open your mailbox in New Outlook of Outlook on the Web.
Note: This feature will NOT apply test emails. Test emails will be sent immediately.