Socially aware sending is an account setting that restricts messages to only send within a specific time window that you can customise. Any messages triggered or scheduled to be sent outside of this window will be held until the start of the the next window.
NOTE: These times are relevant to the time-zone of the account, not the location of the recipient.
To enable socially aware sending:
Ensure you're logged in to the desired account
Navigate to Account > Account Settings
Click on the edit icon next to Socially Aware Sending
Click on the toggle to activate the feature
Enter the start and end times for your daily delivery window