We've now added a scheduler in the e-mail message center which will let you schedule when you want to send your e-mails. Although, currently in beta version, once you've composed your message, simply select the date you want the system to send your e-mail on by clicking on the calendar icon and then type in the time (in Eastern time).
If you leave the scheduler option blank, your e-mail will be sent right away, as they always have! This new option works for sending only and will not take effect if you save your e-mail as a draft or for test e-mails.
More information, please do not hesitate to contact our support team!